Stem Bind

Maybe it's the nasty weather, but a pistol I just finished has a case of stem bind.

It hasn't failed yet, about 600 rds, but it has to be a matter of time - classic dents on the cases from the barrel ramp.

If I read Tuner's comments correctly the first order of business is to check for link riding, and if any exists get rid of it.

Next, possibly to relieve the front of the lower lug slightly - all in an effort to gain a bit of extra space for the round to break over the ramp. Correct? Any other ideas?

On this gun the barrel does not overhang the frame ramp, but it is closer than .030 - I'm guessing about .010 - .015 max.

So next, if the first 2 don't cure it, is to move the barrel ramp back to .030 and re-contour it without giving up case support?

Any input welcome. This frame / slide has been a problem child from the beginning, but I'm determined to make it right (as possible).

Stem bind is a little more complex than just a sharp corner on the top of the barrel ramp, and although rounding that corner can often alleviate it... very often it doesn't help. If the barrel is riding the link hard... holding the barrel lug further than the thickness of a sheet of typing paper off the slidestop pin, it makes the stem bind more pronounced... but those two things alone are only part of a bigger picture, and correcting them separately or together often... but not always... relieve the condition.

Stem bind... technically referred to as "Three-Point Jam" occurs when either the bullet nose actually hits the barrel ramp, or the ogive presses hard on the ramp as the round initially enters the chamber. The first suggests a frame spec problem, while the second usually involves the barrel ramp angle.

When the barrel ramp is struck by the incoming bullet nose, the barrel is pushed forward, and the farther the slide moves, the harder and farther it moves. When the barrel moves forward, it also moves UP. The barrel isn't supposed to move up until the breechface contacts the barrel hood. If the barrel moves forward/up too early, the barrel lugs try to engage the slide's recesses before the slide is in position to let them enter smoothly. The corners of the lugs... slide and barrel... make contact, and as the slide continues to move forward, the barrel becomes wedged into the slide.

At the same instant, the cartridge, now trying to enter the chamber at a higher angle, gets caught between the breechface... the roof of the chamber... and the top corner of the barrel ramp.

In a correctly dimensioned and spec-ed pistol, the round feeds from the magazine... strikes the frame ramp... and angles up so that nothing touches the barrel ramp except at that top corner... usually the widest part of the bullet ogive. This serves to place downward pressure on the barrel... which serves to heep it on the frame bed, maintaining the angle as low as the design will allow... and preventing the barrel from moving up into the slide until the breechface imposes on the barrel hood. If this happens correctly, the round is horizontal fully chambered before the barrel ever moves.

The magazine can also make a signifigant difference, though many will argue the advantaes of the newer designs that have abrupt, early release points.

I'm describing what is essentially a "Wadcutter" magazine, which all manufacturers... both pistol and magazine... seem to have gone to, except for two. One is Colt, who has stuck with the tapered lip/later release feed lips.

This is a compromise that offers the best of both worlds. The other? Norinco. The magazines that came with the Norincos were a virtual copy of the Colt 7- round magazines. Note that only the OEM 7-round magazines from Colt are properly designed. The 8-rounders are wadcutter magazines.

The wadcutter design releases too early and too abruptly, and it doesn't allow a gradual upward movement of the rim as soon as the round starts to strip.

The tapered lip design does. It begins the release slightly earlier, and release is comple slightly later... but the most signifigant thing that it does is that it lets the rear of the case rise as it moves forward, prior to release, so that... by the time the rim is at the release point... the round is entering the chamber on a nearly horizontal attitude... well ahead of the slide striking the hood.

This feature is yet ANOTHER Browning redundancy that allows the gun to accomodate reliable feeding in the event that the ramp angles aren't exactly within spec. Specifically, feed ramp angle too shallow... which throws the bullet nose into the barrel ramp, or barrel ramp angle too steep... which gives the incoming bullet something more vertical to strike. By allowing the butt of the cartridge to rise as it moves forward, it throws the bullet ogive into the ramp instead of the nose. Not an ideal feed... but workable, and much less jam-prone than having the bullet nose hit it. In these, a little light rounding and polishing of the top corner of the barrel ramp usually produces remarkable results.

So... The gamesmen can argue the merits of the Super-Duper, Double Throwdown, Whiz-Bang magazines until the hot place produces icicles from the roof. I've seen the elephant, and know whereupon he poops.

I wondered about mags as well. Primarily using Wilson standard 7rd mags w/ Tripp upgrade kits.

As a test, I also tried 100+ rds through some 20+ year old Colts - these are of the type Tuner describes, I think - substantial taper and fairly late release.

As Tuner noted, the Wilsons taper less and release earlier than the Colts, so that would explain much of the luck that the pistol hasn't 3-pointed yet. But as far as I can tell, and I'm near 100% positive, the brass fired from the Colts showed the same symptoms.

In fairness, the Colt mag springs are also 20+ years old, and both of the Colt mags have the small crack at the stress point at the rear where the relief is cut for the slide rail to pick up the shell.

These are LSWCs, and there is clear evidence of the bullet striking the barrel ramp, sometimes quite low down.

Anyhow, I'll follow Tuner's plan, get rid of any link-riding first, and go from there. This is from the 3-Point Jam monograph in the Tech section.

FWIW - I suspect the frame for this particular gun is out of spec, possibly also the slide. It'll be a challenge.

The mag spring and the follower angle are two other parts of the equation that are important. The spring has to have enough tension to push the rim under the extractor at the rear, and fight the follower's tendency to nose-dive at the front. The angle of the follower, so often overlooked, is an important player in this game... and this is the single that the Wilson-Rogers and similar followers often fall flat unless the gun is dead on in-spec.

These types of followers necessarily match the angle of the magazine... and the angle should correctly be slightly wider than that of the magazine. That is... when the top of the follower is sitting dead flush with the top of the magazine, the rear leg should agree at the corner, but should angle outward near the bottom. Check that angle on your Colt magazine. It can change over the course of twenty years of use. That angle is specified in the blueprints, but isn't really written in stone. Some pistols require a little more open angle, while most function with the print specs.

As a side-note: The early magazine followers... those made prior to 1942... were hardened and tempered to prevent changing. Those made after that were heat-treated, but weren't quite as tough as the early ones. Find an early magazine, and you'll find that the follower is nearly impossible to cut with a file, and they're extremely difficult to adjust compared with later followers. I suspect that the gauged "Drop-In" manufacturing techniques adopted for the WW2-era pistols made it necessary to allow the armorers a little more leeway in tuning the magazines to work correctly with a pistol that wasn't behaving properly... so they backed off a bit with the heat-treatment on the followers. They're still head and shoulders over our current offerings though.

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Stem bind... technically referred to as "Three-Point Jam" occurs when either the bullet nose actually hits the barrel ramp, or the ogive presses hard on the ramp as the round initially enters the chamber. The first suggests a frame spec problem, while the second usually involves the barrel ramp angle.

How do we differentiate between the 2?

When it's the frame, which frame spec is most often the culprit?

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...One is Colt, who has stuck with the tapered lip/later release feed lips.

This is a compromise that offers the best of both worlds. The other? Norinco. The magazines that came with the Norincos were a virtual copy of the Colt 7- round magazines. Note that only the OEM 7-round magazines from Colt are properly designed...

It appears from this that factory Colt 7-rd factory may be the most reliable available?

Brownells lists them at $26 (Carbon) and $25 (Stainless), both .45.

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"strikes the frame ramp... and angles up so that nothing touches the barrel ramp except at that top corner."

Question if possible.

Would the 200 SWC design be the "same" as the 230 RN in that regard?

I got lost trying to visualize Tuner's description of the follower, which should be angled outward toward the bottom. Would someone mind posting a photo of the proper Colt follower?

I have been using the early style Wolff mags (Metalform) with dimpled follower. I assumed that these mags were made with the same machines that make Colt magazines. They have tapered feed lips that are approx .490" from the rear to the release point. I am now testing the new style Wolff magazines made by ACT-MAG. These tubes also have tapered feed lips that are longer than the earlier Metalforms and measure .540" from rear to release point.

Yes, I realize that the ACT magazines have a smooth follower, but the dimpled follower and matching spring fits the tube. However, the long, tapered lip on these mags suggests a gradual release, rather than an abrupt Wad-cutter release. So, perhaps we should add ACT-MAG to the short list of tapered feed lip mags?

I guess my question would be:

Why not just buy the Colt mags, or if anyone makes it, an exact copy, and be done with it?

2nd: Does anyone make an exact copy? Who / what?

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It appears from this that factory Colt 7-rd factory may be the most reliable available?

Well... There are no guarantees. A blanket statement is fraught with gray areas, and it depends heavily on the individual gun. I've seen and heard of flawless reliability from Wilsons and McCormicks, and have seen and heard of just the opposite, regardless of magazine design. have seen many instances of bad function with the above mentioned magazines, that disappeared instantly with the use of Colt or USGI 7-round sticks. Rarely have I seen it go the other way.

I'll say instead that the OEM Colt 7-rounders will provide the best chance of reliable function in any given gun, and that if the pistol won't run with those, there's something else working besides just a magazine issue.

As a final note... Colt is the only current manufacturer who uses the tapered/late-release "hybrid" magazines, if we discount Norincos, which aren't allowed into the country any more. Since Colt has been producing the 1911 pistol non-stop for nearly a century, I'd have to concede that they probably know a little something about the pistol, and how it's supposed to function. I'd also point out that Colt has fewer complaints on the functional reliablity of their pistols than any other. Cosmetics... yes.

Fit and finish... yes. Function? No... and mostly when they come from the factory with what amounts to not much more than a well-finished Shooting Star 8-round magazine with a prancin' horsie on the baseplate.

I've seen one poster here who claims that Norinco's OEM magazines are junk. I'll give 5 bucks a copy and pay shipping for all the "junk" Norinco magazines that nobody wants, as long as they're undamaged. Finish is unimportant.

Conceding the caveat, which should go without saying, but I understand why you have to include it - thanks.

Gonna get some...

I'm still also going to do what I can in the other areas as detailed in the 3-Point Jam writeup, where it makes sense. I really like this pistol and want it to run right. It's twin sure do...and this one's going to also.

gbw, are you able to get any information by doing the slow feed test (without recoil assembly)? If your rounds are indeed striking the barrel at the wrong place and causing it raise upwards before the round has time to chamber, it seems like you could see it happening. Perhaps by covering the barrel feed ramp with black marker you could look for feeding marks that are too low on the ramp surface?

Hi Laz: No need, I can see the marks after firing - I think I mentioned these above. I'm using SWC lead soft-lubed bullets which leave a visible film of the usual gunk all over everything. The feeding marks are clearly visible, from the lowest to highest part of the barrel feed ramp. How often / where are questions I can't answer.

So even though the gun runs, it is not running right. I can feel that it's not as smooth as it should be when firing. I can see the dents on the brass from the top of the barrel ramp (the break-over point). I've also described, I hope, the conditions I can see that may be contributing.

Now, as always, the question is what to do that makes the most sense.

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Would the 200 SWC design be the "same" as the 230 RN in that regard?

The Hensley & Gibbs #68 200-grain SWC bullet, with its long, tapered nose was designed to feed as closely as possible to the 230 hardball's characteristics, and it does get very close... but it's not exactly the same. You may have to advance the release point a little with some tapered-lip magazines, but if the gun is within spec, the parallel lips and early/abrupt release mags were designed with this very bullet in mind.

I've had the Colt hybrid magazines feed rounds loaded with this bullet perfectly, and even through the full-tapered/late release USGI magazines in unaltered, unthroated, USGI pistols... without ramp modification or even polishing. The guns simply don't know the difference between the SWC and hardball...but those particular guns don't seem to do as well with the wadcutter magazines for some reason... though they handle the SWC rounds perfectly in my lightly tuned range beaters. The biggest single factor with the SWCs seems to be in correct barrel ramp angle and shape, rather than the frame's feed ramp. I had one later ORM Colt 1991A1 that wanted to throw an occasional tantrum with the H&G #68 bullet, and playing with the barrel ramp turned it into a rockin' & rollin' fallin' plate killer as long as I feed it with the wadcutter-type magazines and Wolff 11-pound springs... which all my magazines have.

On an interesting note... I came into a small batch of brand new, unused WW2 production USGI magazines from three contractors. Risdon... MS Little... and Scovill. When I tested the spring tension at full compression, I could tell very little difference between the GI mags and those with lightly used Wolff 11-pounders. Once the Wolff springs have taken a set and have gone through a few cycles, the tensions and rates are practically identical.

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How do we differentiate between the 2?

Easy one...

When the frame ramp is causing the bullet nose to hit the barrel ramp, you'll hear and feel a definite "Ka-chunk" as the round chambers. If it's bad enough, you'll get bullet setback with one or two chamberings. This one is caused by the frame ramp being too shallow...more than 31 degrees...or the corner at the top being rounded off, as is noted whenever a duffer overpolishes it. That corner is important.

Note: I've seen several instances where the tapered lip magazine...either USGI or Colt "hybrid" greatly reduces or even eliminates the telltale "Ka- chunk." One of the pistols that this was noted in recently belongs to a fellow forum member... and the gun is a Colt "Gunsite" model.

The second... noted most often by hard scrape marks on the side of the case or the bullet ogive... is caused by the barrel ramp. Either too steep, or with a sharp corner at the top. Light rolling of the corner or polishing usually reduces or eliminates this one, but sometimes it requires setting the barrel ramp further forward, and recontouring the whole ramp...which can include reducing the severity of the angle.

This fix can also help to get the bullet ogive over the top of the barrel ramp corner with a shallow frame ramp angle, but also usually requires losing a little more case head support than is prudent. Not an issue if you're using reduced-pressure ammo for most of your shooting... but can be an issue if the headspace is a little long and you shoot a lot of hot-rod stuff in the gun.

And in fact, the H&G type do ding the brass somewhat less. The Lyman 452460 also do well with the Wilson mags, although some dents appear. Most of the testing has been done with a bullet that is neither - it's a 200 swc, but with a sharper and smaller nose. I'll do a picture tonight of the bullet and barrel marks. Frame ramp angle is 29 - 30 degrees, slightly too steep, and also not deep enough - about .310".

Both headspaces are near minimums, so I've got a little room to work there.

One problem is that if I move it out to 31.5, I'll lose some of what little frame bridge-shelf I do have right now. Barrel ramp angle is stock Kart so far, except I've flattened the very bottom edge to get just a little more shelf - but this is very slight.

Another point, the barrel on this pistol does not hit the bridge, and I'm wondering about elongating the top of the crosspin link hole to both lower the barrel at feed position and remove any possible link riding.

Regarding Colt or USGI mags, I know where to get the Colts. But what about the USGI stuff out there? Since there were so many contractors making USGI mags, how we determine if they are the good ones or not?

These for example: http://www.ammoman.com/45MAGS.HTM

Meant to add, both headspace measurements are near minimums, so I've go a bit of room to work there.

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Regarding Colt or USGI mags, I know where to get the Colts. But what about the USGI stuff out there?

Rumor has it that Checkmate industries still offers the standard USGI-style magazines with the full tapered lips. You have to specify that design. They also may have some overruns made to Colt's specs. Wouldn't hurt to ask... but be specific.

Checkmate was the main contractor for Vietnam-era GI magazines. Good mags, but not as nicely finished as the WW2 contractors produced.

http://www.checkmateindustries.com/

I'm having the same problem - smiley dent in brass - on a gun that has just been rebarreled. The barrel is a "drop-in" Storm Lake bull that in a previous life had a supported chamber, but which has been cut to standard configuration. If I ignored the appearance of ejected rounds, I would be extremely happy. I suspected that the barrel "throat" (entrance of chamber, from 4:00-8:00) was too steep (vertical), right from the start. Without moving the whole thing forward, I moved the "corner" inward a few thou, and blended it, then rounded the corner, and while it runs well, I still don't like knowing that it isn't right.

I appear to have all of the classic symptoms: The first few rounds from a full mag feed less smoothly than when the mag is half-empty. Smiley-shaped dent in the case. The gun feeds more smoother with the extractor removed. By removing some extractor tension, and changing from a 14# recoil spring to a 12#, I have the gun feeding without hesitation (and the case dent reduced to less than half its previous length and depth). I've used both McCormick and ACT-MAGs, and couldn't see any difference. I inspected the link, and at no point in its travel, until it's rotated beyond 45 degrees, is the edge of the hole above the lug; that is, the slide stop pin cannot ride the link. The barrel is fully linked-down within .25" of slide travel. How much rounding of the chamber entrance ("corner") can be done, without compromising safety? How much brass should be exposed, above the extractor groove? That is, if my throat is still too vertical, how deep can I move the "corner", and still be safe?

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"I had one later ORM Colt 1991A1 that wanted to throw an occasional tantrum with the H&G #68 bullet, and playing with the barrel ramp turned it into a rockin' & rollin' fallin' plate killer as long as I feed it with the wadcutter-type magazines"

I have one of those and it's very reliable, you'd be proud, with the SWC.

It does hit the barrel ramp though, I can see the marks after shooting. I wondered whether the SWC "gets away with it" better than a 230RN...so to speak. It's too reliable for me to fool with...I'm dumb, but not that dumb!!

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How much rounding of the chamber entrance ("corner") can be done, without compromising safety? How much brass should be exposed, above the extractor groove? That is, if my throat is still too vertical, how deep can I move the "corner", and still be safe?

The answer to that is... It depends. I know. Sounds like a cop-out, but it applies in full measure. The unknown factors are total headspace... and, if over mid-spec... which direction it comes from. If it's due to excessive chamber depth, you can cut quite a bit. If it comes from leg fit and breech opening/separation under pressure... not much. Happily, most over-minimum headspacing in failry new guns is split between the two.

If your barrel ramp is steeper than it should be... and depending on the frame ramp angle, even a correct/in-spec barrel ramp angle can be too steep for reliable feeding... rounding the corner may not do any more than turn your smiley face into a grinny face. ---> Rounding the corner off is mainly a fix for a non stem-binding condition in which the sharp corner is the only real issue, unless you cut so deep into the bottom of the chamber that it takes on an oval shape. Bad JuJu.

In such cases, reshaping and changing the angle of the barrel ramp is the correct approach. You lose the same amount of case head support, but you also correct the stem bind.

How much is also dependent on unknowns. Case construction is one. Some brass will tolerate less support more readily than others. Ammunition average pressure levels is another big one. Loading down just 5% can mean the difference between unscathed brass and bulged brass. Even with +p pressures, the .45 ACP is still a relatively low intensity round, and it takes qyite a bit of non-support before it becomes dangerous. Of course, that changes with lug wear and deformation/setback... but if the barrel is well-fitted, it'll take a goodly amount of use to see it.

Oh yeah... Almost forgot!

Yes. The extractor can have an effect, and even mimic a stem bind by preventing the rim from getting high enough on the breechface to let the round break over at the right time. It pushes the barrel forward via friction... side of the case or bullet ogive against the top corner of the barrel ramp. This usually shows up as a skid mark, but can sometimes produce the telltale mark just below the case mouth...although it's usually a little lower than the true stem bind cut... and generally less pronounced.

Tension AND geometry at the bottom of the tensioning wall can figure into the condition, as can a sharp corner on the bottom of the claw. This is one of the reasons that most smiths go ahead and do these mods on all new extractors, whether or not it's actually needed. It can't hurt anything, and it usually smooths out the pickup, even on guns that are well within spec.

So when looking at feed ramps, with a loaded mag installed, one will see that even though the ramp extends way below the area of the bullet nose & magazine... the bullet will only contact the the very upper edge of it... or break over point.

just for what its worth, I couldn't believe the difference in the sound of the slide dropping on my 'modern' 1911 (ka-chunk!) versus 1911Tuner's pre- War(I think?) USGI pistol (slap!), the USGI pistol feeding SWCs no less.

The more I learn, the older I want my 1911s to be.

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one will see that even though the ramp extends way below the area of the bullet nose & magazine... the bullet will only contact the the very upper edge of it... or break over point.

Ideally, that's what you want... but the bullet nose should hit no lower on the barrel ramp than about a 64th inch.

Rob! I forgot about me doin' that little demo for ya with that old 1919 Colt... and the Rand... and the... Did I do it with the '25 commercial Government Model? I forget.

They fed the SWCs from the old magazines as slick as green grease thru a queasy goose, didn't they? Kinda laid waste to the "Common Knowledge" that the 1911 was designed to only work with hardball.

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So when looking at feed ramps, with a loaded mag installed, one will see that even though the ramp extends way below the area of the bullet nose & magazine... the bullet will only contact the the very upper edge of it... or break over point.

I'm confused. Of which ramp are we speaking? The breakover pt. is on the barrel ramp, which surely does not extend below the magazine, that would be the frame ramp. The bullet is likey to hit the frame ramp most anyplace, depending on reaction coming out of the mag (dive, straight, up). It's also possible with the H&G for example, for the bullet to miss the frame altogether and hit the barrel.

I'm talking about the feed ramp on the frame.

The bullet can only hit the ramp (frame) as far down as the top of the magazine. Which if you look, isn't very far from the top of the frame.

Depending on the mag style and timing of it's release, will play the important aprt of where it will hit. Of course there are spring factors etc. as well.

Also out of curiosity - This thread is about excessive stem bind and the likely result of a 3-point jam. We've talked mostly about ramps (frame and barrel), barrel throat sharpness, headspace, and magazines.

I've just re-read the '3-Point Jam' tech note, there is a great deal about links, premature barrel rise, and lower lug front contours. Almost nothing about magazine feed type, barrel or frame ramp shape, nor barrel ramp edge reduction, except 'polishing ad nauseam.'

What am I missing? I ask this with all sincerity. I figgered the thread would develop along the 3-point jam writeup lines of linking and lug contours.

I'm happy this other information has surfaced as well, but I do sort have a chicken and egg question about which to try first?

Obviously the less invasive things first (mags), then links, then I suppose it depends on which is most out of spec - but I really don't like that approach. Once we start cutting, I'd rather go for the highest probability of success regardless of whether it's the most out of spec component or not.

I'm also betting on soon to be shortage of Colt 7-rd mags from Brownells!

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...The bullet can only hit the ramp (frame) as far down as the top of the magazine. Which if you look, isn't very far from the top of the frame.

On the Wilson magazines it is possible substantially below the bottom of the frame ramp on my pistol, which has admittedly too shallow ramp - but it's still quite deep into the frame. I can't remember on Colt and you may well be correct for them.

On my Colts, the Wilson mags put the bullet where it's intended to be. Like Tuner said, about 1/64th" below the top of the frame. Just barely into the frame feed ramp before it heads to the barrel.

From what has come across my bench, a high percentage of feeding problems are magazines... with actual 3 point jams being very low... but they still happen.

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I've just re-read the '3-Point Jam' tech note, there is a great deal about links, premature barrel rise, and lower lug front contours. Almost nothing about magazine feed type, barrel or frame ramp shape, nor barrel ramp edge reduction, except 'polishing ad nauseam.'

Mainly because it's basically a primer that covers several things to check for in a stem bind/3-point jam condition... from a smithing perspective instead of a return to basics... which, surprisingly... most people either don't want to hear, or don't want to admit that their setup failed because of something so simple and straightforward.

Why no mention of different magazine styles? Truthfully, because I've grown a little tired of plowing the sea... and the indignant responses that I've gotten over the years by having the audacity to suggest that someone's beloved (Pick your favorite brand) may be the problem rather than the cure. I've even had people become hostile after proving it to them on the range. Their main argument is that they "Have to have that 8th round because they have a better chance of cleaning the rack at the plate match without reloading.

Weary of spending time and effort turning a "Jammin' Jenny" into a Timex watch... pro bono... and then finding that the owner has returned to using the 20-pound recoil spring, and the (Pick your favorite) magazine that was causing the problems to start with... and having them come and tell me that my work "fell apart" and that the pistol still isn't functioning. When I point out that changing the system that worked, the response is usually: "Well, so-and- so gunshop expert told me that you didn't know squat, and that I needed to go back to what was in the gun to start with to keep from damaging it." This... even though the gun hadn't missed a beat in over 2,000 rounds... until things were changed back as per the gunshop commando's advice.

I know that there are many pistols out there that do fine with (Pick your favorite) magazines. I've seen it. I've also seen'em run like a scalded hound for months, and choke during a match stage... and then return to being reliable for many more months, with no rhyme or reason... and choke again at some point later. I haven't had a misfeed that wasn't the result of a bulged round that came off my badly worn press in many years and tens of thousands of rounds... and very few of those. I've recently started using a new press for the seating operation, and have had no more problems.

I haven't broken a steel extractor in over 20 years... and with no need to reset the tension on any, except when I recently left all my much-used brass with enlarged rims on the gound, and turned to a new lot. Over the course of five years, the rims had caused the extractors to self-adjust to the larger diameter. I reset the tension and have had zero problems. Two of these extractors have been in their homes for approaching 90,000 rounds. Two others were changed out during a rebuild...not because they were giving problems... but just because it felt like it was time. They reside in my range box as spares, in case some unfortunate should should break one in the middle of his range trip.

Weary. Yes... Color me weary.

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From what has come across my bench, a high percentage of feeding problems are magazines... with actual 3 point jams being very low... but they still happen

Odd. My most-often noted local issues come in the form of 3-Point Jams... to some degree. They range from the occasional hard jam to the maddening intermittent failure to go to battery. Almost without exception, the guns give the telltale "Ka-Chunk" sound when feeding the top three rounds... which becomes less pronounced the fewer rounds there are in the magazine... but still present. In about half the guns that this has been an issue, the "cure" comes with a USGI magazine... much to the owner's surprise, and often chagrin. Some offer to buy all that I have... but I politely decline with a suggestion to "Start Shoppin."

Moving On

Whew! Now that I got that off my chest... let me add that the near-rant wasn't directed at anyone in particular, and though I do get weary, I will endeavor to persevere. (A quote from Chief Dan George in The Outlaw Josey Wales) I will... because there are still many people who want to better understand how the thing works... or at least is supposed to work... and determine what may be happening to cause a malfunction, and how to best go about correcting it... hopefully without invasive surgety. To wit: Most problems are simple to correct. You may wind up settling for one less round... but sometimes compromises are called for if near-100% reliability is your desideratum.

I will... because I very much like to mess with the 1911 platform, and because I view the problems that arise as a challenge and an adventure.

I will... because, by and large, the people that I meet through my efforts here and in person, are good people who can darken my door for about any reason or no reason. I've met a good many through this and other forums... some have been here once for a tune-up, and haven't been heard from since, while a few others have become real friends who call me or come by just to shoot the breeze, or... in Kartracer's case... to visit with his favorite Collie. (Just playin' witcha, Joe.)

Some have come from far away. Others live close by. Some are brave enough to drink the coffee... and some decline... understandably.

Many will hopefully feel as though they can drop in any time... or call ahead to make a plan... depending on the length of travel time they have.

I will endeavor to persevere because of them... and in spite of the "others."

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You may wind up settling for one less round... but sometimes compromises are called for if near-100% reliability is your desideratum.

An extra round that never gets fired because your gun jams is just extra weight to carry around.

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Mainly because it's basically a primer that covers several things to check for in a stem bind/3-point jam condition... from a smithing perspective instead of a return to basics... which, surprisingly... most people either don't want to hear, or don't want to admit that their setup failed because of something so simple and straightforward.

I'm just trying to fix a problem, and am perfectly happy to admit to whatever the cause may be... basic or complex, I couldn't care less, and if I caused it then so be it - just so long as I (we) learn from it. We're all here to learn, I hope. I was just surprised at the two completely different tracts given the same exact subject - had no idea the tech note was only the smithing / complex half of the story, it doesn't say so, and most of those articles do cover basics. I certainly didn't intend to step on toes nor to provoke a near- tirade.

Gbw, glad you brought up the feed problem you are currently having. I'm on information overflow, but after reading Tuner's info several times I'm beginning to understand a little.

Let's say you have done some good work fitting your barrel and achieve a snug fit in battery with plenty of barrel drop in linkdown. The bottom lugs hit the VIS first and you think you have hit the jackpot. Now, it seems that the gun may not feed well based on exactly where the round strikes the barrel ramp. Well, my gun goes KaChunk even with ball ammo, so I have more work to do also. If you come up with the right combination, let us know!

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Odd. My most-often noted local issues come in the form of 3-Point Jams... to some degree. They range from the occasional hard jam to the maddening intermittent failire to go to battery. Almost without exception, the guns give the telltale "Ka-Chunk" sound when feeding the top three rounds... which becomes less pronounced the fewer rounds there are in the magazine... but still present.

What causes the Ka-chunk, and why on the top rounds? For the other half (non- magazine caused), what's most often the problem? And the cure(s), since I'm imposing.

My particular problem gun is, I think, out of spec, but I want still to get it as good as I can.

In this case out of spec means (and I'm fairly sure, but not experienced enough to be positive), the following

1. The cross-pin to vis is about .440 instead of .449, so I'm short there.

2. Frame ramp angle is 29-30 degrees - close, but still out 1.5 - 2.5 too steep.

3. I don't know how to measure this, but putting a new barrel up against the VIS does not leave near the .031 shelf, well less than half of that.

In short, the whole frame measures to me as if it's mashed .025 - .035 too close together between the rear of the mag well and the slide stop pin hole - things just don't seem to have quite enough room to get their doin's done.

Never forgetting the clear possibility that I've overlooked something else, whether basic or not,

The gun Ka-chunks on the top rounds with every mag I've used. Not always, but enough. Oddly it hasn't jammed yet, but it's gonna, and it puts a golf ball smile on a fair percentage of the brass.

N.B. I do have one magazine that will jam it every time, I'm gonna keep it as a souvenir - unknown make, round follower, wadcutter release, and one side releases about .075 before the other - the gun tries to chamber those rounds sideways.

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Let's say you have done some good work fitting your barrel and achieve a snug fit in battery with plenty of barrel drop in linkdown. The bottom lugs hit the VIS first and you think you have hit the jackpot. Now, it seems that the gun may not feed well based on exactly where the round strikes the barrel ramp.

Sad to say, not true - I do not have plenty of clearance. It's adequate, barely. No sign of polishing / crashing, and I've blued the barrel top to be sure. VIS contact is very good. Lower lug / crosspin contact in battery is very good. Upper lug contact in battery is very good. Zero vertical clearance in battery, no signs of binding. Ball usually feeds clean from old Colt 7rd mags, but most SWCs don't.

Where the round strikes the frame ramp seems to me, and from this thread info, to be mainly dependent on the magazine, and to a far lesser extent on the angle of the ramp. Magazines can be changed, as Tuner emphasizes.

What happens next, after we hit the ramp, and how to improve it, are the other main questions. In the frame ramp? Barrel ramp? At the link? Front lower lug profile? All of the above? If so, in which order - I suppose it's case dependent and I haven't sorted it out yet myself. The immense value of experience! But we'se learnin.

Thanks guys. I don't mind argument and debate. In fact, I invite it,because it opens a technical discussion as to WHY one thing may work, and the other may not. Debate brings on questions. Questions beget answers. It's when it gets personal that I lose patience. When the challenger comes off as insulting and/or condescending... Well... I've learned what the "Ignore" feature is for, and have started to use it for the first time. The "Oh, Worshipful Master! We all bow to your superior knowledge, and are forever in your debt for allowing us to benefit from your vast experience" approach doesn't cut it with me any more.

Anyway...

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What causes the Ka-chunk, and why on the top rounds? For the other half (non-magazine caused), what's most often the problem? And the cure(s)

Ever noticed how the top 2 or 3 rounds sorta "float" at the front, without support from the round underneath? That causes the rounds to take a dive into the ramp as they start to move forward. There's a pivot point there that parallel feed lips tend to maintain. When the bullet nose hits the feed ramp, the cartridge is caught momentarily, fighting to turn upward on the ramp angle... but it's being held down at the rear, and the rim is at a sharp angle against the breechface... making it harder for the rim to get under the extractor. The round climbs the feed ramp against spring tension from the recoil and magazine springs... still at a fairly sharp angle... and it hits the barrel ramp. Ka-chunk!

With the tapered lip magazine, the round still nose-dives, but the gradual release allows the cartridge to rise slightly at the rear just AS the bullet nose hits the ramp.

The relationship between the bullet ogive... the contact point... moves from the meplat to the ogive... creating a larger and smoother contact point. A gentle camming surface, for lack of a better term. The front of the cartridge can turn upward under less resistance... and it does. As it turns and moves up... so does the rim, since it's also being released, moving up as it moves forward. The bullet nose slips over the top corner of the feed ramp at a shallower angle. The rear is still moving up, which brings the round closer to horizontal.

The bullet ogive hits the barrel ramp high... on or very close to the corner. The barrel is held down against the frame bed, and the case starts over the corner of the barrel ramp... still at a slight angle, but the straight side of the case has the barrel under full downward force. The barrel is trapped between the side of the round and the bed, and can't move forward and up. The rim is almost completely under the extractor.

The magazine releases the round, as it's nearly chambered. The pivot point of at the corner of the barrel ramp and the ogive's contact point with the roof of the chamber work to break the round to horizontal as the slide pushes it forward. Rim placement under the extractor is completed as the slide strikes the barrel hood and forces the barrel to move forward and up.

It's hard to explain, but the light comes on with a visual demonstration... but I'll try.

Hold a round in between finger and thumb, as though it's in a magazine. Move it forward, as though it were being stripped. Angle it down, then abruptly back up, and then angle the rear up as though it were being pushed under the extractor.

Now... repeat it, but this time as the round moves forward, keep the nose and rim on the same plane...as though the feed ramp was very long and gradual. Instead of the cartridge having to turn a series of corners, it moves forward and up at the same time as though it were sliding up an inclined plane, fully supported along its entire length by a solid block of steel that has an angled base that agrees with the inclined plane that it and the cartridge slide on.

Maybe this will help...

A square block of steel is cut in half diagonally. Each piece now has a 45 degree angle. Hold one piece on its square edge parellel to the floor. Position the other piece so that its angle sits on top of the other's angle, and the two pieces agains form a square. Slide the top piece backward. As the top piece moves backward, it's upper edge moves downward. Now... imagine that a cartridge is on top of the upper piece.

Slide the upper piece forward, so that the moves up the inclined plane of the lower piece. The upper edge and the cartridge of the moving piece remains parallel with the floor... even though it's being raised. It's being raised evenly from front to rear.

I am one of those...

Since this thread focuses on the role of magazines and feed ramps in either preventing or causing 3-point jams, I thought I'd offer these observations for everyone's amusement.

I am one of those hard-heads who must crash and burn before I learn certain fundamentals. I spent today re-evaluating the progress (lack of progress) on my current project gun, with particular emphasis on magazines and ramps. For the life of me, my ramps appear to be sufficient and correct. They are neither polished, nor overly rough. Nor is my frame ramp cut down lower than the slide stop and mirror polished, (as some of my custom smithed editions are). Angles are ok. Setback ok.

But somehow the feeding of ball rounds (haven't even tried SWC) is far from smooth, often stopping in mid feed, or refusing to even get the round out of the magazines. Ka-Krunch is the sound it makes. I recently gave away my Wilson 47D magazines because I could tell these were not working, especially on the last round. That left a bunch of Metalforms (got 'em from Wolff) and some new ACT-MAGs.

After reflecting on Tuner's information on feed lips I started looking hard at exactly what was what. The early Wolff-Metalforms have short, parallel feed lips. These mags feed, but not reliably. The bullet nose heads straight for my barrel ramp and hits it directly at the mid-point. The barrel rises up, and you know the rest...

The newer ACT magazines have long parallel feed lips. Since the rim does not rise slowly as the round is being fed, the bullet does a nose dive and stops when it hits the frame somewhere below the level of the s.s. window. A small light went on here, that begins to explain why some magazines would kind of work sometimes, but not in all the guns. And so on. This is where everyone gets to say 'told you so'. Trash can now full of new ACT-MAGS.

I did take one ACT magazine apart and modified the rear end. The rear seems to hold onto the round with particular vigor, but that only serves to make the nose diving effect more pronounced. Smoothed out this strange design 'anomaly' and tried spreading the feed lips to resemble a tapered lip magazine. This spring steel is hard! I did achieve a sloppy tapered lip effect after some serious bending effort; and even though feeding was not completely smooth, I immediately saw a big improvement in the overall smoothness of feeding. But by that time the magazine looked pretty beat up and having served its purpose, joined its friends in the trash can.

So, here is just one guy's puny experience in learning things the hard way. Some new explanations appear for why certain guns would jam, but not always. Never could nail it down to a magazine, a type of ammo...always a frustrating mystery. First things first, though. Time to start hunting around for some Colt magazines.

That's the story.

Brownells lists Colt 7-rd .45 mags for $25 or so. I have 3 older Colt mags, but I mean old. 25 years or more. They did not affect feeding much one way or the other. These are the hybrid type Tuner describes, tapered lips and later release. I'm going to re-spring these and try them again, also check the skirt angle. All of them also have the characteristic crack - this crack is horizontal from the corner formed at the back of the mag where the sharp angle is formed by the relief cut for the slide pick-up rail to hit the rear of the cartridge. I'm not sure it hurts anything but it cannot help. If the newer mags have this same form of cut, it may be a good idea to radius the angle to relieve the stesses there.

On a separate note, I just got some new Schuemann barrels today for some stainless guns I'm going to do. They have a very pronounced chamfering sort of relief cut at the edge of the chamber (on top of the ramp). Far deeper and larger than I was planning to put on the Karts, and must be there to relieve stem bind. I'll do pics of these later today, and I'm very curious to see how much of the cartridge is left unsupported after they've been fitted. They also, as Iron Bottom mentioned in the riddle thread, are not releived aft of the bushing area in lock up. I'm going call Schuemann and ask if his barrels are normally relieved by the builders, or if the bushings are just fitted loose enough to prevent binding.

Old Colt mags

gbw... Yes. The cracks can make a big difference if they're bad enough to allow the lips to spread... as can the follower angle and the spring tension.

And too, with some pistols, they won't make a difference. Those types are usually suffering from some other malady, and usually in the specs... and about half the time, in the angles of the feed and barrel ramps. Which brings me back to a point that I've often made: Reliable feeding... or lack thereof... is determined more by the angles than the surface finish or any high-dollar trick magazine design. If the angles are right, the gun will eat any reasonable cartridge you can stuff into the magazine. AND... consider this carefully... the angle and rise/release timing of the original tapered lip magazine design is part of that system. The parallel lip design is a variant that grew from the use of lead SWC bullets in the early NM competition, as was the flared barrel ramp. The GI mags were tweaked and timed for an earlier release, and finally the lip taper was straightened to force the short, sometimes balky ammo to pop up at the rear quickly and effect a better chance of reliable extractor pickup... before the round could become uncontrolled. it worked well with short, SWC rounds, but didn't do so well with longer ball ammo, or bullet profiles with a ball-like ogive.

On the upside, they tend to work pretty well with truncated cone hollowpoints, such as the old-style Hydra-Shok and the PMC Starfire bullet.

Hornady's XTP also falls into that category, especially the ones that are loaded to an OAL of less than about 1.220 inch.

garrettwc in post 16 on this thread gave a link for what are purported by the seller to be G.I. mags. Does anyone know if these are actual G.I. mags with tapered lips, not cheap copies, and if they are any good? Less than half the cost of Colt mags would be a nice savings.

Bill that's the same thing I was wondering in my post. The only way to know would be to order a couple and check them out.

From what I gathered either in this thread or another one where we discussed magazines, mags stamped with a cage code as those are, came later in production probably post Vietnam era and may very well have the newer wadcutter lip design.

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...AND... consider this carefully... the angle and rise/release timing of the original tapered lip magazine design is part of that system. The parallel lip design is a variant...

Tuner - it's interesting to note, as I follow these discussions... I took a closer look at the mags that came with my K9 - which has been 100% reliable for the ten years or so that I've had it - and the lips on those mags look exactly like what you are describing on the original 1911 mags (though smaller, of course ).

Freeme... Interesting how the more things change, the more they stay the same. Somebody who was involved in the design development of your K9 saw the difference... and understood.

I just came upon one of the best and most accurate descriptions of the function of the 1911 pistol that I've ever seen on an internet forum. I'll credit it to Robert Hairless, and I wish I'd said it.

He said:

"The Model 1911 is an entrancing machine. Each part works in conjunction with others even when the functional interrelationship isn't apparent or doesn't seem to exist."

I will use this bit of simple, straightforward wisdom often...

Corners and Cracks

I'm sure some of you already knew this, but I sure didn't.

Photo below is of a new Kart on left and new Schuemann on right. I was very surprised at how much chamfer Schuemann puts on the top of his barrel ramps. This can only be to forstall 3-point jams. I haven't fitted a Schuemann yet and it'll be very interesting to see how much unsupported cartridge I see v. the Kart. If I can remove that much from the Kart safely I think the stem bind will be more or less a thing of the past.

If you look closely you can also see that the Schuemann is not relieved (turned down) just aft of the bushing - I asked about this, Schuemann recommends the new 3-point bushing from Strayer.

My guns feed from Wilsons (7-rd w/ Tripp Upgrade) much more smoothly than from the Colts (below).

BUT the Colt mags are old and worn out, and the cracks are clearly visible - lower one is Armoloyed.

Also of interest - the Wilsons present the cartridge much higher initially than the Colts. Guessing around .040" higher, and from what I understand, this is similar to what Tripp mags do.

Does anyone know if the newer Colt mags present higher?

That is amazing! I've been slowly, through cut-and-try, increasing the amount of relief on the "corner" of my barrel, to help alleviate the case dings, and I'm nowhere near that kind of "secondary feed ramp", but concerned that I might go too far. I had a Schuemann Classic "pre-fit" barrel in a Colt M1911A1, and still use the barrel as a handload chamber checker, and it looks nothing like that in the throat area. If you can take some pics of chambered rounds, to show the amount of exposed brass, it would be very interesting.

If you could take pics of both barrels side by side with rounds in both, showing a good side veiw to see how much or less the case the being supported.

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If you could take pics of both barrels side by side with rounds in both, showing a good side veiw to see how much or less the case the being supported.

The barrel is short chambered and not fitted yet (see other post where I'm begging for tips on using a chamber finish reamer!). As soon as it's done I'll do just that - I'm very interested also.

Perhaps someone else already has one they could show us...

The heavy chamfer was done to give the incoming cartridge a better chance of gliding over the top of the ramp in pistols that have angle spec or other tolerance stacking issues within the frame. It gives the hobbyist a better shot at success in fitting the barrel and havint the gun feed and go to battery reliably... but it does cost case head support. After finish reaming the chamber... deeper... it may not be as much of an issue as it would be if you just made the cut on an existing barrel to smooth out the feeding or address a 3-Point Jam condition. In that light, it's the perfect example of what NOT to do to a barrel ramp.

I have cut a secondary ramp angle on occasion... but not nearly to that degree. It's also often referred to as a "Booster Angle" and is most often used on barrels with an integral ramp, which are usually a bit too steep... like the ones that Springfield sticks into their Micro Compacts.

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The barrel is short chambered and not fitted yet (see other post where I'm begging for tips on using a chamber finish reamer!). As soon as it's done I'll do just that - I'm very interested also.

The Schuemann barrel is marked "Classic"; isn't that their line of "pre-fit", might-drop-in barrels? That is, the chamber, hood, etc., should already be cut to should/might fit dimensions? My Classic was a near drop-in.

No, I did ask Schuemann about this before ordering - the Classic is the closest to the standard 1911 form, as opposed to his bull barrel, or hybrid comp, or any of the other one-off types he makes, also that the classics are oversize and need fitting in upper and lower lugs, and hood length and width, as well as finish chambering. I also tried to insert a cartridge, no luck, not even close. But I won't know for sure until I go to fit one.

Chambering specifications provided with the barrels call for a chamber final depth of .898 + .010 max. So he isn't calling for a deeply cut chamber at all.

And I guess that makes sense to me in the end - the first thing that happens after ignition is that the bullet is released from the casing and the casing pushed back to the breech face. So would a deeper chamber really give any additional support? Before max pressure is reached? Or would it serve to lower max pressure by larger volume? I don't know, but it seems to me neither would lower pressures in the unsupported areas much (but I'm only guessing and could well be wrong here). But in any case Schuemann doesn't call the deep chamber.

So I'm back to being surprised at the size of the chamfer and the likely large unsupported area. I hope he knows something we don't. I'd like to see his other barrels to see if they have the same chamfer.

Shuemann does call for the hood length to be cut to be in contact with the breech, that means to me he absolutely doesn't want any additional dynamic headspace introduced that can be avoided, or I guess it could be to gain max accuracy. Also, he calls for SAAMI standard pressures only, but that's a pretty standard warning.

I tried some of the recommendations in the Tech Notes section under the 3- Point-Jam writeup, mainly with keeping the barrel down as long as possible, by eliminating any link riding and by re-shaping the front of the lug to wait as long as possible before it begins rising.

I believe it helped - although it wasn't that bad before, the gun runs smoother.

I still have nosediving into the feedramp on the early rounds, and I need to get the ramp to 31.5 (it's 29 - 30 now), and to find the magic magazine that won't nosedive with this gun. I also have not done anything yet to the barrel. But it's getting there.

BTW - Looking at the photo of the barrels again, I'm beginning to think the Schuemann ramp isn't angled as sharply as the Kart. I'll have to check.

If that's the case, the chamfer is not as severe as it looks. The acid test will be to measure how much of the cartridge is exposed in each after installation.