Reliability Tweaks 2
The next thing that I tend to is sharp corners and edges on the slide.
Burrs and sharp corners are the breeding ground for cracks, and a big part of reliability is in the gun not breaking.
The ejection port is one area that seems to develop cracks. I go around and around the port with a piece of 320-grit wet or dry paper and smooth every sharp edge that I can get to. It doesn't take a lot to break or roll those corners, and if you're careful, it'll never be seen without close inspection of the bare slide.
Likewise the corners of the slide rails should be broken lightly with a stone.
A minute 45 degree bevel along the length smooths out the cycle and gives dust a place to go. One or two light strokes per side is usually all that's
required. The firing pin stop is another part prone to cracking under hard use. Use a flat miniature file... needle file or Swiss pattern... to bevel the corners, and don't forget the hole. You can use a countersink to lightly chamfer the hole on both sides. If you don't have a countersink, you can use a cone-shaped grinding stone from the Dremel board at Lowe's. Don't use the Dremel for this... Twirl it with your thumb and finger. All you want is to break the sharp corner.
Look to the front of the slide where the bushing goes. Feel for any sharp corners just inside the frong, and use the paper to smooth those out too. A little goes a long way.
Look to the disconnector or cocking rail in the center of the slide. If it shows a circular pattern left from the milling operation, use the edge of a medium India stone to smooth the edges off. Don't try to remove the marks... If you remove too much metal, you may create a problem with the disconnector function. The trick is to knock the high spots off to let it ride over the top of the disconnect smoothly. $ or 5 passes with the stone should do it. Finish it up by wrapping a piece of 600-grit wet or dry paper around the square edge of the stone and make another 4-5 passes. A drop of honing oil on the paper will polish the rail nicely. Sewing machine oil is a good substitute.
Look at the breech face. If there are any tool marks there, use a piece of popsicle stick with 600-grit paper on it to smooth those out. Again, don't try to get a mirror polish. Just knock off the edges. Use the little stone that you got at Lowes to spin around for a couple of seconds in the firing pin hole. Don't use a lot of pressure here. All you want is to smooth out the sharp corner.
When you're through, flush all the left-over abrasive and dust with carburetor cleaner and allow the slide to air-dry for 15-20 minutes.
Regarding disconnectors. How far back should the slide be when the disconnector is disengaged and the gun becomes able to fire? Is it bad if the hammer falls and is caught by the half cock. Does this damage the sear?
Also an arbitrary question... how much (in inches) should the frame overlap the dust cover of the slide?
If you mean how far out of battery does the slide have to be to push the disconnect out of engagement between trigger and sear, I like to see it happen with the slide .100 inch or less out of battery. To get an exact measurement, I'm afraid you'll have to wait until my Kuhnhausen books arrive... maybe today, but probably tomorrow. I figured that it was high time for me to have a look at'em, since I've never done more than thumb through Volume 1 at a gun show about 5-6 years ago.
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quote: Is it bad if the hammer falls and is caught by the half cock. Does this damage the sear?
Yes and yes. While the ordnance-spec pistols will tolerate this a few times without adverse effect, it's not a good thing. A fine-honed sear can be ruined by the half-cock, which is why we see half-cock notches on some aftermarket hammers that are designed to catch the sear only in the middle, protecting the areas that engage the hammer hooks.
The half-cock "shelf" found on Series 80 Colts and late-production Springfields are kinder and gentler on sear noses than true half-cock notches.
Be aware that bending the middle leg of the sear spring to lighten the trigger pull can cause the half-cock to catch the sear, as can pulling the trigger with the slide slightly out of battery. Bending that middle leg has its limits. Don't overdo it.
quote:
Also an arbitrary question... how much (in inches) should the frame overlap
the dust cover of the slide?
.065 inch... Plus/minus .005 is about right. I may be off a little on the tolerance here, but on a non-critical dimension, a tolerance of .010 is usually allowable. In some areas, a 64th is okay. (.0156) Again, I'll check the Kuhnhausen 1911 Bible when it gets here and give you a blueprint dimension.
Will it be obvious that the sear was damaged? Will it be obvious on inspection of the sear?
.100 sounds like a wee bit on the far side. It is no where near that. If the primer was hit by the firing pin when there was very little lock up,(like at .100-.125) would it cause any damage, hot smoke in the face?
Is it okay if the frame is longer than it is supposed to be?
Stinkyshoe asked:
Will it be obvious that the sear was damaged? Will it be obvious on
inspection of the sear?
Usually. You'll notice a burred edge on the tip, and possibly a chipped or cracked area. If the sear is made of good stuff, it would take several half- cock stops to do damage signifigant enough to compromise the function of the gun. If a finely-tuned trigger job has been done, you can cut the number of stops roughly in half, depending on just how fine-tuned it is. A "Match" trigger job will be damaged easier than a street trigger job.
And:
.100 sounds like a wee bit on the far side
It is. I would prefer to see the disconnector break contact at much less slide travel than that. .100 inch is the outer limit because at .100 inch of travel, the barrel begins to unlock from the slide, and if a round should fire out of battery at that point, the case head support is too weak. An out-of- battery discharge at that point in the slide travel *probably* wouldn't result in a blown case head, but then again...it just might.
And:
was very little lock up, (like at .100-.125) would it cause any damage, hot
smoke in the face?
Probably. Since the horizontal support from the breechface would be reduced, the case would likely back out of the chamber on firing enough to let hot gasses escape backward. Damage? Probably not, other than maybe a bulged magazine or cracked grip panels. The 1911 is a pretty tough cookie, and the .45 ACP's working pressure is fairly low.
If your disconnector breaks contact at the .050-.060 mark, so much the better. The farther the slide is out of battery when ignition occurs, the weaker the support. At .050-.060 travel, the barrel and slide are still locked, though not as solidly as when they're in full battery.
There is a limit to how close you can get. If you get one that breaks contact the instant the slide moves, a very small piece of grit can prevent the gun from firing at all. Those need to have the timing slot in the slide scraped a little.
Finally:
Is it okay if the frame is longer than it is supposed to be?
Longer where? From the slide's impact surface to the ends of the rails? To the end of the dust cover?
The only reason I could see a problem with a overly short disconnector(or one the disengaged too soon) would be that if you could pull the trigger faster than the gun could cycle. Is that possible?
Would a half a dozen half cocks stops (if I promise never ever to do it again with a cherry on top) amount to much?
Would it be better to half a disconnector/slide match up that allowed the trigger break sooner than when the trigger will only break when the battery is all the way closed? Just in case some gunk or something were to get in there and push down on the disconnecter and make it not fire(one of those hypothetical tactical never going to happen situations )(oh now that I just typed this I see that you addressed it)
My question regarding frame length stems from having a full length frame and wanting to make it a "standard" GI length. There would be a region of over lap where the frame would be covering the dust cover.
What is your opinion of bake on moly coats?
You mention the 45 ACP being a lower pressure cartridge. It seems to me to be ideal because it is economical to shoot, doesn't have 36,000psi chamber pressure like some cartridges, and seems to be effective as a weapon.
Stinkyshoe:
if you could pull the trigger faster than the gun could cycle. Is that
possible?
Oh yeah. Some of the racegunners double-stack shock buffs to decrease the cycle time on their pistols so the gun can keep up with their fingers. The other reason for this is to give the pistol less time to move between the first and second shots so they can make two close hits on the same sight picture.
quote:
Would a half a dozen half cocks stops amount to much?
Not unless you've got a delicately honed sear and a 2-pound trigger... Most smiths that do trigger jobs like that use modified half-cock notches that protect the sear in case of a half-cock followdown. On a stock sear, a few stops wouldn't amount to a lot of damage unless the sear has an internal defect, which would eventually cause it to fail anyway. Even if the sear nose breaks completely off, the gun will stop on the half-cock if that's a concern during Condition 1 carry.
quote:
My question regarding frame length stems from having a full length frame
and wanting to make it a "standard" GI length. There would be a region of over
lap where the frame would be covering the dust cover.
If you mean that your gun has a full-length dust cover that sits flush with the endof the slide, you can shorten it, but most guns made like that... as nearly as I can remember from the pictures... don't have the scalloped area on the end of the slides. It might look a bit chunky with the dust cover cut back to standard length.
quote:
What is your opinion of bake on moly coats?
They're fine for blackening stainless or in-the-white sights, but tend to scratch, flake, and peel from large surfaces such as frame and slide. The more careful you are with the metal prep before using the coat, the better it will hold up. Bottom line is that it's still just a paint job. Personally, I'd rather use cold blue paste. I've seen some remarkable results on some guns that were blued with Brownells Cold Blue Paste, and have had good results using it to touch up holster wear and scratches.
quote:
You mention the 45 ACP being a lower pressure cartridge. It seems to me to
be ideal because it is economical to shoot, doesn't have 36,000psi chamber
pressure like some cartridges, and seems to be effective as a weapon.
Yep. That's one of the big advantages with the .45 ACP cartridge. It leaves a generous margin for error in the event of an overcharge or bullet setback. The pistol will withstand far more pressure without damage than you might imagine. Jim Keenan plugged the barrel with a threaded rod and fired GI-spec rounds repeatedly in one with no damage to the pistol. I don't suggest that you try this. His experiment was carried out in a closely controlled enviroment.
For what it's worth, Ned Christiansen repeatedly fired a 1911 without a recoil spring, and there was virtually no difference in the timing of the barrel unlocking from the slide, and no visible damage to the frame, though I'm pretty sure that a few hundred rounds would probably result in some pretty bad battering in that area. The 1911 is over-engineered for its cartridge, and for those WHOOPS! moments that seem to find a way to happen.
The .45 Super and .460 Rowland are proof that the 1911 is over-engineered. The 10mm should also be added to this list. People always talk about cartridge pressure, but it is slide velocity that is my main concern.
I have never hot rodded the .45 ACP, (much ). However, I am guilty of hot rodding the .38 Super. Have not blown a case yet, and have gotten good results, high velocities and accurate. However, the lighter bullets of the .38 Super keep slide velocity down, and if the brass is strong enough I see no problems.
The situation changes in 10mm, and the various .45s. Seems like it would be very easy to pound one to pieces, even if the pressure was acceptable. That, and the fact that I am trying to get over an injured hand keep me from experimenting with extreme loads. (OK, I admit it, the superior wisdom that comes with advanced age is a contributing factor).
I would like to know how much of the strength of the 1911 comes from iiproved steel. I know that the slides of WWI era pistols was definitely softer than modern day guns. The difference is amazing.
That slide velocity is absolutely a factor in the overall reliability of the gun... and the 1911 is very much over-engineered...for the .45 ACP round... but there's another area where cartridge pressure can have a dramatic and sometimes destructive effect. The impact area of the locking lug faces in the frame and on the barrel.
When pressures go up, the amount of lug engagement gets more critical. 70% engagement will do for a .45 that doesn't see a lot of use, but a high- pressure round that is coupled with high recoil forces generated by a 200- grain bullet can beat the lugs up pretty quickly, or even shear them off unless there is nearly 100% engagement. Barrel fit is more critical for the Big 10 than for the .45 ACP.
You can run a rough check on yours with a blue felt-tip marker. Color the barrel lugs all the way into the corners and shoot the gun a few times. hand- cycling won't show you much. You'll have to shoot it. Look to see how far down on the lug the blue has been removed to get an idea of how much of the lug is bearing the brunt of the load. This isn't precise, but it will get you pretty close.
That sounds like a good check to run. I would do it this afternoon, but it is probably going to rain.
It is a shame that my chronograph will not measure slide velocity. I can get ballpark figures on a pocket calculator, and watch to see where ejected cases land to see if the two ballparks are in the same zip code. Of course, when you consider the different weights of different barrels, it gets a little more complicated. My Delta Elite has two barrels now, the original 10mm and a 357 SIG barrel, which is a little heavier, since the hole in it is a little smaller. This slows slide velocity some. Bull barrels, and or comps would do so even more, but I have not explored that area well.
Sometimes I wonder if JMB would recognize his child after all of our modifications? Which changes would he approve of?