I'd like to describe a barrel/link fitting situation and ask for advice. The pieces are: Kart NM barrel, Caspian Gov. slide and frame. I removed metal from the upper lug recesses of the barrel while watching the amount of engagement increase slowly. I now have about .045" lockup, and can see the barrel hood is just touching the slide behind the #1 lug face. At the same time the firing pin port is perfectly centered.
Then, the barrel feet were fit (minus link) to stand on the slide stop with the slide in battery.
At this point I installed a standard .278 link and noted that the lower link hole is about .010" "below flush" on the lug feet. That is, the slide stop will not go into the frame because the link hole sits too high. In fact, I have to go to a #5 link to get a flush fit with the barrel feet in lockup.
So, if I remove metal from the feet, to allow a .278" link to be flush, the barrel upper engagement will be decreased and the firing pin hole will not be centered. The barrel seems to drop clear by the 1/4" mark with the #5 link but I am uncertain whether the long link will introduce other problems down the line.
Use the long link? Toss the barrel and start over?
I am no expert on barrel fitting, but I would first try the #5 link instead of filing the barrel legs. Remember the golden rule, always work on the cheaper component.
My logic says that it is important to have good lock-up on the lugs, and the barrel feet to ride the slide stop shaft for positive lock-up. The link is used to unlock the barrel. If the #5 unlocks the barrel properly, why destroy the good lock-up you had?
Yep, that was my thinking as well, and it made sense to me. Make the barrel stand on the slide stop, pressed hard against the upper lugs, after centering the firing pin. That's what we've been shooting for all along, right?
Then, after the barrel goes into battery with a solid vertical lockup, you don't really have much to say about your link dimension. I can see that standard parts can be forced to work at the expense of a tight vertical barrel lockup. So many things to control all at once!
No offence, El Commandante, But over the years I've noticed that working on the "right" part gives much better results and you don't ruin the cheap part.
Looks like a lot of frames and slides are out of spec nowadays. The VIS is cut for a standard link and barrel and slide lug engagement takes a back seat. If you get decent lockup, you may have to go with a long link and run into problems with the VIS and or frame bridge. Or cut the lower barrel lug to fit a shorter link and give up your solid lockup. Nice choices. You will probably have to remove some material from the frame somewhere. VIS I suspect because that longer link may not provide the needed barrel and slide clearence since the larger arc of the longer link will move the impact point of the lower barrel lug back and will stop the barrel at a higher position than a shorter link. I've been told by someone I trust that that bowtie is just a cheap and cheesey way of creating a VIS and I concur. And after John Browning got beat down on his prices, he probably had to take some short cuts. I think another poster in a different thread nailed it when he concluded that the bowtie currently in vogue was not the proper solution to creating an Impact surface. But do what you must do. Just my opinion anyway. And worth every penny you paid.
No offense taken, as I said, I am nowhere near being an expert in barrel fitting. What I just said was, that before cutting the barrel legs, I would first check if the #5 links is OK. It may be possible, as you say, that with the longer link, the barrel doesn't come down properly, or you may be surprised to find that it does. What do I know?
A point I have not seen discussed.
Removing .005"-.010" from the back side of the lower barrel lugs.
.100" thickness is fine.
Can give you that extra necessary linkdown when using a longer link.
I believe you are exactly right about using the #5 link, El Commandante. If the lockup is good and the firing is centered correctly, the longer link is the only way to go in my opinion. I was just saying that the price of a part doesn't always determine or fix the problem. I've got the same situation going on. But with a .288 link, the bottom barrel lug is impacting the VIS way too high and is affecting the barrel/slide clearance when out of battery. I do not want to give away any lug engagement to correct this problem since this would lead to a loose lockup and borderline barrel and slide lug engagement. As the last poster mentioned, taking some material off the back of the bottom barrel lug may correct the problem, but I really didn't want to cut away this area. There is a local machine shop and I am going to see if they can or will move the VIS back. Who would ever know anyway? And if it doesn't work out, I've got some TIG rod for 4340 and can probably scrape up the ducats to machine away this unfortunate decision.
Machining back the lower lugs or the VIS has the same effect.
Realize this though... you will also be decreasing the feed ramp to barrel gap. Many times it is a compromise between feed ramp depth/angle, gap and cartridge support.
It seems as if the forward wall of the mag chute on Caspians is a bit too far forward. This leads to a further compromise as described above.
It's a balancing act. Borrow a bit from Peter to pay Paul.
Thanks for the comments, gents. Using the #5 link, I find that if I mark the rear of the barrel bottom lugs and the belly of the barrel with Hi-Spot, I do get a mark on the VIS and, suprisingly very little if anything on the main bed itself. The barrel does not stand on its feet, because the feet have been shortened too much already by Kart. The barrel seems to be stopping on the belly that is forward of the lugs, and I'm not sure whether that is OK. Seems as though a little material removal on the bottom of the barrel will relieve it enough so the timing will be correct.
The Caspian frame has been machined with a bow-tie VIS, although it is not as deep as some I've seen. I don't like it one bit, as the contact area has been reduced to a very tiny area, albeit "correctly" located at the top of lugs.
Sure is fun to juggle all these variables around. At this point I freely admit that I don't have the experience to decide which dimensions are most important (except for headspace). I'm going to stick with a hard vertical lockup, however, since that gives me the maximum lug surface to bear the forces of firing.
For now, use the #5 link and check the linkdown/drop timing to see if the barrel is clear of the slide at .250-inch of slide travel. If it doesn't clear sufficiently, check to see if the barrel's vertical drop is being stopped by the link in compression, and being held off the bed.
If that looks good, flip the gun upside down and pull the slide rearward briskly.
The barrel should disengage and link down as smoothly as it does when held upright. If it doesn't, you've probably got a VIS mislocation...too far forward.
Of several Kart barrels that I've used... both Easy-Fit and full or "Hard-Fit" none have had a mislocation of the lower lug too far rearward.
The bow-tie cut is a quick-fix for a forward VIS, and it works nicely. The issue that I have with it is that it leaves a very narrow strip of material at the top of the VIS... where it takes the full impact of the barrel... and it deforms quickly under hard use, until eventually, the VIS is too far rearward.
Thanks, Tuner. The barrel has dropped fully by 1/4 inch of slide movement. The gun unlocks smoothly when held upside down also. Your description of the details of barrel crashing sure gives me the shudders - definitely don't want that!
I originally thought that achieving a good solid barrel fit was the result of careful measuring and planning. This time, at least, things sort of "fell" into place in some areas, and had some unpredictable outcomes in others. Part of the learning process, I guess.
The #5 link is .290 center-to-center, and it's apparently timing the barrel drop correctly. What I glean from that is...Your slide is sitting .012 inch higher than the top of mid-spec from the slidestop crosspin hole. Vertical tolerance stacks will do that sometimes, and I've seen worse...much worse.
When (and if) I fit a barrel in a pistol, what do I have to do? Strive for maximum interference between the slide and barrel lugs and riding the slide stop shaft, then find the proper link to bring the barrel down and from then on adjust anything that needs to be adjusted like the VIS or the barrel legs?
Or shall I start with the standard link and see what I get with it?
Add this question to those by John in Post #13 of this thread: If a new barrel is going to be fitted in a 1911 that has had its rails and barrel bed lowered about 0.010 inch, what changes (if any) need to be made to the normal barrel fitting procedure?
Not so fast
John and Niemi, I think you are jumping past a few steps. There is a logical order to the fitting process and decisions have to be made along the way, instead of all at the beginning.
Going for maximum upper lug engagement is a good place to start, but be prepared to improvise and remember to go slow. Kuhnhausen describes a nifty tool made from a scrap barrel that will give you the ability to measure from b.f. to lug surfaces - so if you've got the tools, that may be a place to start. Without a special tool of some kind, you are going to be eyeballing this measurement, using Cerrosafe, or modeling clay to get a grip on whether the lugs are equalizing. Here are a couple things to keep in mind while fitting the upper lugs.
a). Don't forget to make your "sloppy fit" bushing and use it during the
fitting process. Otherwise you will have no idea what the barrel is really
doing.
b). Remember that the barrel cants upward at the rear when in battery,
relative to the slide. That means that initially you will have a very thin
line of contact between the slide lugs and the the barrel recesses, (in the
vertical dimension). So if you are looking for full contact, the barrel
recesses have to be cut at a slight angle to the barrel axis. Machinist ink or
felt marker will be of little use here because there is no relative movement
to make a mark. So modelling clay or hi spot may do the job for you.
c). Keep an eye on the hood area just behind the #1 lug face. The barrel
won't be able to move upward any more if that area is already touching the
upper inside surface of the slide.
d). All the while, you must stop and check the relationship between the
firing pin port and the chamber. Punch out a primer from a spent case, put the
case in the barrel and look through the firing pin hole toward a bright light.
That relationship will tell you when your vertical lug fitting is done.
So, let's assume that your firing pin is centered on the chamber and you have achieved a respectable amount of vertical engagement. Now is when you have a look at whether your barrel has enough clearance with the slide to link down. Then, lock the barrel, without link, into the slide with your nifty locking tool. Use a Wilson lug cutter if you really must or hand fit the barrel lower lug so that the barrel stands firmly on the slide stop, and so that the slide is near to the in-battery horizontal position.
Only now is when you break out the links and see which one will fit without compromising the hard vertical lockup you have achieved. Only now is when you scope out some of the other dimensional problems that need attention like the barrel bed, VIS, and ramp. That is, of course, my 2 cents worth on doing things by hand. You won't be making any money this way, that is for certain. I'm leaving the slide about .100" from fully forward, thinking that a few rounds at the range may take up some of the slack here. As the slide settles in a little at a time I now see that the #4 link will work ok. Guess I got a little ahead of myself trying for a Les Baer "press fit".
Not that I am going to be fitting any barrels any time soon, but thanks for this, I appreciate it. Good tutorial.
Give it a try
I encourage you to take the plunge. I'm certain you can do better than 90% of the guns that are currently available, and if you fail miserably there is still your old barrel waiting as a backup...
It's not easy to get barrels here, it requires a special import license and then it is written in the same license with your guns. Don't confuse good old US with Greece!
Corrections Applied!
Haste and cranial flatulence have struck again, I fear.
I posted that the #5 link is .281 inch C/C length. That started as a typo, and I estimated the other dimensions from that same typo, for some obscure reason...My bad. I've corrected it.
Bear with me, gents. It's been a long week...
Going a little further... now that I have my brain cleared... The advertised link on-center dimensions are nominal, and have a tolerance of +/- .0005 inch, which means that with two given links, there can be a maximum difference of .001 inch. Also, other brands besides Wilson are offered in .003 increments that will allow you to find one that will effect an exact fit most of the time. The downside is that you'll either have to keep a large inventory on hand... or determine exactly what you need and order... and even those have that +/- tolerance... so be prepared to adjust the link slightly by elongating the large hole in one end or the other.
Opening the top of the hole... closest to the lug... doesn't change linkdown timing. Opening it in the lower half delays it in the same way as a longer link.
Generally speaking... if it needs to be opened in the lower end, I much prefer to step up to a longer one, unless the amount needed is .002 inch or less... and I try to limit opening the top to a maximum of about .003 inch, though .005 or more isn't out of the question... IF... the link correctly times the barrel. As a rule, if it needs to be adjusted more than .003 inch, you probably either need a shorter link, or the lower lug dimension is wrong for correct vertical lug engagement. Opening the top doesn't really have a negative downside since it neither changes barrel timing, nor does that area of the link come under any tensile stresses.
Lazarus, good advice in post 15 with one tiny nitpick regarding the use of a spent shell casing to center the FP hole. I would look through the muzzle end of the barrel instead of the firing pin tunnel. The reason for this is that the primer hole in the shell casing is much larger than the firing pin hole in some slides (Springfield, for example). If you are looking through the FP tunnel in one of these slides, when the top of the hole in the shell casing is aligned with the top of the FP hole it will appear that these two holes are aligned. Now, if you turn the slide around and look through the muzzle you will see that these two holes are eccentric to one another.
Don't ask me how I found out about this!
Ok, then.
Good point, Greg. In this particular case I'm dealing with a 9mm size f.p. port (tiny hole), which seems to be the same size as the priming port in the spent shell. Also, the smaller 9mm f.p. can be used to double check the alignment by pushing it forward into the case. With the larger standard f.p. your method would make more sense.
I like the Brownells tool to center the bore with the firing pin port. It will align both sizes of firing pins with the bore. Of course with my eyesight, every little bit of help is welcomed.
Think about this
Kuhnhausen's tool, and the one sold by Brownells are useful to evaluate the raw slide dimensions. For a given slide, you will practically need to turn your own piece of brass stock to just fit. The result will indicate whether or not the firing pin port has been drilled at approximately the correct place in the slide. However this alignment tool will be of no use to your barrel fitting efforts because the vertical position of the barrel depends upon exactly how you fit the upper lugs. So in this case, the use of a spent shell works out pretty well.
You must be trying for the Holy Grail, Lazarus. If I can get within a few thousandths, I'm happy. But with any barrel/slide combo, the Brownell's tool will let you see if you are off in any direction. North, South, East and west.
Center Strike
I'll take the "For what it's Worth" category for 10!
A dead center firing pin strike isn't one of those things that I put in the "Must have" lineup. Nice, but unnecessary except in a bullseye pistol chasing an inch at 50 yards. .010-.012 inch vertical displacement is of no practical concern, though you wouldn't want that much lateral variation. Good vertical lug engagement is more pressing. Some slide and frame specs require a barrel with slightly oversized dimensions from chamber axis to lug slot, with the lug height dimensioned from the bottom of the slot...which may be a custom-made item these days, and an expensive proposition.
Also, fwiw, I put a primer in the case, put slide, fp, fp stop, link, sl. stop, bushing, barrel, frame together. Coat primer with sharpie. Load EMPTY primed case right side up, so if strike is off you know which direction. Hit fp with punch and fire the primer. It all only takes about 10 minutes and you don't have to guess where it strikes. As Tuner says, a few thou vertical doesn't really matter much.
Well, that's one way!
I guess setting off a primed shell is one way to have fun in the basement. I'd rather stick with just sighting down the barrel through the priming port. A little modeling clay stuck into the de-primed shell could also be used to gauge the position of the strike. Remember, the primer can drive a bullet halfway down a barrel by itself so it isn't just a harmless little device. That said, it does kinda sound like fun.
Will be doing some test firing on the gun tomorrow and see if I'm able to do the basic stuff. You know, chamber a round, fire it, and extract the case. Sounds like a lot at to ask for at the moment. Will report.
Mixed Results
Well, I had some interesting results with the test firing. Put about 100 rounds of ball ammo downrange with minimal jamming. Next-to-last round jams mostly. Cases were extracting, but the spent cases were mashed up around the mouth and all seemed to have extractor marks on the rim. I know extractor marks mean that the extractor is trying to pull the case out too early - don't have any other indications right now. No evidence of battering of the slide lugs at all.
Feeding is jerky both at the range, and while doing the hand cycling test. It seems that the bullet nose hits the frame ramp and just stops with the round about half way out of the magazine. That is, the round has moved forward about 3/8" so the rim is half way to the magazine lip release point. That would indicate that the frame ramp is too far rearward or cut at the wrong angle. It definitely is cut too shallow (Vermont style), but will report more measurements on the next post.
At this point I am figuring that the frame bridge is too high, accounting for a rough beginning of the feed cycle. The gun works smooth as silk otherwise, and has the required barrel drop clearance - too bad it seems to be out of spec. A great learning opportunity presents itself!
I'll post some dimensions next time now that everything appears to fit together properly.
I'm a little curious about one thing, Lazurus. Does the link go past vertical (toward the muzzle and I believe this is very important) when your pistol is in battery? The one I'm working on drops the barrel too fast and I haven't opened up the link anywhere. The link going past vertical has to delay the barrel drop some. Think I'll locate the center of the link pin on the slide at the point the barrel is in battery and compare with the slide lock pin drilling on the frame with the pistol assembled and find out if I'm gonna have any barrel feet left.
Ok, here we go
Thanks for the comment I.B. If I understand you correctly, you are asking if the link moves rearward of vertical when the slide is in battery. The answer is yes, the link is slightly rearward of vertical. At this point the only remarkable problem is the short frame ramp. See below.
The gun fires and ejects, with occasional jams. Spent brass is mashed about the mouth, but does fly rearward and toward the right at about 45 degrees (expected). Empties that jam are facing forward with the mouth half out of the ejection port at the top of the port. The barrel hood is doing the mashing. Brass marks on the very top of the ejection port, also just below the bottom of the ejection port on the right side. (Slide is an A-1 cut, no lower/flare. We are using a Vermont A-1 frame and Vermont classic slide.)
- Using #4 EGW link. Barrel does not ride the link noticeably, but s.s. is free of the barrel lugs when barrel is linked down. Barrel stands on the slide stop when in battery.
- I have not elongated the link holes.
- There is approx 1/16" normal gap between frame ramp and barrel ramp when barrel is linked down.
- .437" horizontal distance between s.s. CL and the VIS
- Top of frame to s.s. CL is .447 vertical distance
- Frame bridge depth is .074"
- Top of frame to mag release CL vertical distance is 1.540
- Vertical length of frame ramp is too short at .200" Please see photo in this post:
Chuck Rogers Post
The gun in the "before" photo has about twice as much frame ramp as my Vermont frame. Incidentally I do not own a dremel, nor have I sliced and diced the frame or barrel feed ramps! If we are looking for a frame ramp similar to the finished photo in Chuck's post, some serious metal removal is indicated.
I have about .045" vertical barrel lockup, with approx .015" clearance between barrel and slide in link-down. The barrel hits the VIS at .228" of rearward movement. Can't tell for sure if barrel is fully linked down at this point, but there is enough clearance for the barrel to move. The slide is parked happily with the rear of the slide and frame within 1/32" of each other. The thumb safety fits perfectly into the slide at this point. Without recoil spring and disconnect, the gun cycles smoothly (no ammo) simply by tilting it 45 degrees either way. Gun also cycles smoothly upside down.
Gun does not hand cycle (with ammo) smoothly. Rounds seem to stop when the bullet nose hits the frame, before they touch the barrel, before the rim is loose from the mag lips. I'm going to call this condition the "Vermont Style" since I'm informed that gunsmiths "everywhere" demand these dimensions.
I think that's everything. I am now open to comments, suggestions, or flames. Thanks!
You "should" have ~ 1/16" between the barrel lip and the frame when the slide is fully back. If so, slowly and /carefully/ see if the case slides under the extractor. Or you could pull the slide off and check the clearance and for burrs. It "should" have a slight bevel to help the case slide beneath it.
For a faster diagnosis of extractor problems in feeding, just remove the extractor and see what happens.
Oh Well
The rim of the cartridge moves forward in the magazine only about 1/4". In that state, the cartridge rim is still in the magazine, and nowhere near the extractor. As a double check, I pulled the extractor out with no change in my basic feeding difficulty. By looking at a few other guns, some of them Vermont Style, I can see that my frame ramp is way too shallow, even though it seems to be cut at the correct angle of 37-1/2 degrees. Vertical depth on the frame ramp is about .200" A typical ramp depth is .380" and can even go further as Chuck points out. I believe this is why the bullet nose just stubs itself on the frame ramp; the ramp is too far towards the rear. Unfortunately, this is a job for a mill. I don't want to do this by hand.
Lazarus, I think you posted saying your slide was .100 back and you were going to shoot it into spec. Perhaps you meant .010. Thats the reason I asked about the link.
Yes, at first I didn't know how much movement to expect on the slide after shooting. I see now that if you are fit up correctly and not just partially fit, there won't be any movement. And, I didn't get any.
Here's a couple of photos showing the now famous "Vermont Style" feed ramp.
PICTURE 404
PICTURE 404
Can you show the ramp with a loaded mag. inserted? I can't see how, if the ramp extends below the forward edge of the mag, the bullet could hit below the ramp, regardless of depth. I guess it could by a very few thou., if they were dead even, but not by much.
Just got my Caspian problem child runnning (see Lowering Frame Bed), I'll post pics and specs and report soon.
BTW: Feed ramp polish was required. It was cut rough, horizontal machining grooves took a death grip on any bullet that hit it.
Gbw, I'll try to get a photo up of a loaded magazine in the frame. The bullet nose does hit my frame ramp, but to the best of my ability the ramp sits a little too far rearward, preventing the round from easing out of the magazine. So, in this case it doesn't help much if the nose hits the ramp; the ramp has to be in the right place to begin with. A subtle, but important difference.
This ramp has .200" vertical depth. My other 1911's have ramps that are nearly twice that. How deep is yours cut? The polishing may have masked the real problem...
Perhaps, but I can tell you that it was similar to feeding the bullet across a file - lead or copper shavings could be found on the ramp. This was before the gun was finished, and I polished the ramp before I shot it. I'll check the depth tonight - I'm assuming the measurment is vertical from the top of the frame?
You can easily make a jig to polish or deepen the ramp, using an L shaped peice of steel - it takes about 20 minutes. It does take some fussing to get it clamped on the frame in the correct attitude. Then you can polish / deepen the ramp yourself. Watch for centering and angle changes if you remove any significant amount of steel.
But be careful - moving the ramp forward will reduce the depth of the barrel bed, on mine there is barely enough depth for the barrel / frame step, and this is AFTER lowering the bed over .020, which lengthens the bed. (Kart NM barrel).
I also think (?) the cartridge is supposed to still be partially in the mag. when it starts it upward deflection by nosediving into the feed ramp - otherwise control would be lost. If I understand controlled feed and 1911Tuners post on the subject correctly.
Ok, here we go
Here is a photo of a loaded mag in the frame:
Loaded Mag in Vermont Frame
The next one shows the top round advanced so that the nose is touching the ramp. Note where the rim of the cartridge is relative to the magazine lips. It doesn't look like the round can begin to get into a nose-up position.
Round Advanced Toward Ramp
gbw, could you describe the jig you have in mind a bit more? I'm not coming up with anything mentally yet. Thank you.
I'll try, sure. Mine is made from a 3/16" piece of welding rod - whatever you use it needs to be fairly stiff. Bend about a 4" piece into an L shape (right angle).
File the interior of the long leg flat. Easiest way is by draw filing. This will clamp against the side of the frame. The shorter leg will be suspended horizontally across the frame above the ramp. (Use heavy paper under the jig and clamp so you don't mar the frame. I use a C-Clamp, carefully).
Now is the harder part - locate on the shorter leg the center of the frame width. A bit of measuring and re-measuring will do it. File a notch on the jig (on the shorter leg that will be held over the ramp) at the center point of the frame. This notch will guide your dowel - I used a piece of brass rod about 6" long, turned to .010 under the radius of the ramp cut. But I think wood would do fine.
Glue a piece of 280 or 320 paper over the first 2" of the dowell.
Hardest part - clamp your jig so that the notch guides the dowell into the magwell at the correct angle to polish the ramp by moving it back and forth into the mag well against the ramp. Your handy protractor will help you get the correct angle, or if you trust Caspian (I did, although I'm not sure I should have), just cover the existing ramp in layout blue and adjust the jig until the dowell removes all of the blue with one very light stroke. This takes a bit of fussing around to get it right. Now you know the dowell is moving at the same angle as the ramp.
Check again that your dowell is moving parallel with the frame sides and is centered in the frame width, and the angle is correct.
Polish out the tool marks only, by moving your polisher back and forth with light VERTICAL pressure - although in yours I don't see any.
Once again, be careful of the barrel / frame step, and not to remove anything til you're sure. HTH
Laz, on your very nice photos, on the frame barrel recess (bed) I think I see barrel marks all the way to the rear on both outboard sides. Is it possible the barrel is overhanging the frame?
Hi Lazarus; Just by eye, I'd estimate the magazine in your second picture will relase the cartridge after about another 0.3 inch of forward travel. My relatively new Colt magazines release a cartridge after about 9/16 inch of total travel. I think your ball cartridge will have plenty of opportunity to get nosed up by the ramp before it's release by the magazine (assuming it's released where the lips' inward flare abruplty dissappears).
FWIW, the earliest magazine release point I recall reading about was 1/2 inch, and that was for mid-range semi-wadcutter taget ammo. I've got two magazines tuned for this and they work just fine, but all I ever shoot is target stuff. I'd guess the release point of the magazine in your second picture would be about 9/16 inch - which should be OK.
However, if your concern is that the magazine lips will prevent the cartridge from being nosed up by the ramp I can't really even guess. Only have experience with magazines with lips that gradually open up to the release point.
Quote:
I'll take the "For what it's Worth" category for 10!
A dead center firing pin strike isn't one of those things that I put in the "Must have" lineup. Nice, but unnecessary except in a bullseye pistol chasing an inch at 50 yards. .010-.012 inch vertical displacement is of no practical concern, though you wouldn't want that much lateral variation. Good vertical lug engagement is more pressing. Some slide and frame specs require a barrel with slightly oversized dimensions from chamber axis to lug slot, with the lug height dimensioned from the bottom of the slot...which may be a custom-made item these days, and an expensive proposition.
FINALLY! I was wondering when someone would comment about the necessity of a center firing pin strike. I've built countless Bullseye 1911's in years past, without the oversized first barrel lug, and the strike was always well off- center. And they'd all print well under X-ring size or they got rebuilt.
BTW, when I want to see where the firing pin strike is, I use a range rod with a firing pin hole-size tip on it and put a little Prussian Blue on that tip. It'll tell you exactly where the strike will be.
Quote:
FINALLY! I was wondering when someone would comment about the necessity of
a center firing pin strike.
Make that two voices of reason...
Hey! What can I say, Bob? I'm a practical guy and take a practical approach to the 1911. If it shoots into an inch at 25, I'm as happy as a duck in the middle of a nest of fat June Bugs. If it shoots two inches at 25, it's still good to go for my own purposes.
If it'll go bang, shuck the empty, kick it out the port, feed the next round...and repeat that for as long as my hand will stand up to it...I ain't gonna stress over a few hairs breadths of firing pin concentricity in a primer that probably ain't dead centered in the rim anyway...
Picture worth 1000 words. My Cheap Ramp Polisher, and as I use it. Works better with 2 clamps, less tendency to rotate. This was set up just for the photo.
Anyone got a better way? I'd sure be interested.
I checked this frame, ramp cut at 31+ degrees, right on. Depth was .290, kinda shallow, as Lazarus also found.
Lazarus
8th December 2006
gbw, thanks for setting up the jig and taking a photo. You have a very nifty device there, and it has the advantage of polishing the ramp in the proper feed direction. Also, thanks for mentioning that you found the polishing step to be important. I was trying to be stoic and figured that the "controlled feed" principle requires some resistance. Maybe not as much as I now have. The ramp comes rough from the machine shop, and of course the tooling marks are against the direction of feeding. If you look at the photos of my frame you can see the copper marks on the ramp, (as you mentioned). Fortunately, I have a little extra horizontal room on the frame bed so the ramp can be cut just a bit deeper without compromising the required ramp "gap".
My pleasure. If anyone has a better system I'm always wanting to learn.
BTW, a very similar jig can be used as a guide for lowering the frame bed but it's slow. And you must use thinner material or the dowel will be too high, I use a nail. It's clamped across the dust cover, but be sure to put a filler block inside the dust cover before clamping.
Also, remember that the pressure is vertical, and on the business end, pressure on the jig end of the dowel should be just enough to keep it in place.
Finally, you still have to be careful that you don't let the polisher wander off center - check often.
By the way, the mill experts use a 1/2" diameter mill to recut the frame ramp. Ideally, a steel rod just under half inch should work well when it is covered with fine paper.
Yep. But 1/2 " should be fine, and is easy to find, I doubt the few thou added by the abrasives would matter... I couldn't remember the dia. and didn't want to guess.
Don't know what radius a Caspian receiver feed ramp is milled to, but the Ordnance Dept. spec for this is 0.236 + 0.005 inch for a mid-spec diameter of 0.479 inch. If Caspian's is close to this, I'd suggest finding a piece of rod, dowel, or tubing about 7/16 inch dia. and use duct tape to build it up so that, when wrapped with the abrasive, its diameter more closely matches the ramp. Then use GBW's spiffy guide to keep the angle correct.
I used this tape-wrapped-dowel (acutually brass tubing) method to lower the barrel bed in a receiver. Nice thing is when switching to a finer grit abrasive paper (which will be thinner), the tool's diameter can be increased with another layer of tape. And, with a fixture similar to GBW's to guide the tool, the bed ended up pretty straight, with little detectable (by me, at least) rounding at the ends.
Make a big pot of coffee before you start. As I recall, the bed lowering went at the rate of about 2 or 3 thousandths per hour - because only short strokes could be taken. LOL