Troubleshoot Finale'.

[John Travis]

Unnamed semi-custom 5-inch gun with two problems. Owner called me on a rainy Saturday afternoon.

First problem was intermittent failure to go to battery. All critical frame and barrel specs were good.

Magazines not the problem.

Extractor wasn't clocking, or at least not enough to cause a problem

Owner, recognizing an issue, admitted that he had worked to try and correct the problem, and in so doing created the second without completely solving the first.

Ejection was a little erratic and weak, but acceptable...until the last round came out.

On the last round the case would be stuffed partway back into the magazine, depressing the follower and preventing the slide from locking open. Magazine forces the extractor off the case rim. Slide runs forward and tries to chamber the empty case which is sitting on a slight upward angle, and crushes the case between the breechface and the barrel hood.

This happens every time with all magazines.

Noodle it and see what you come up with.

 

[Catfish]

On the last round the case would be stuffed partway back into the magazine, depressing the follower and preventing the slide from locking open. Magazine forces the extractor off the case rim. Slide runs forward and tries to chamber the empty case which is sitting on a slight upward angle, and crushes the case between the breechface and the barrel hood.

I dunno what caused his F2RTB problem - probably just a weak spring? - but he futzed around with the extractor and now it doesn't have enough tension.

 

[John Travis]

probably just a weak spring?

Nope.

If anything, the spring was a little heavy.

but he futzed around with the extractor

He did, but the tension was good.

 

[GymB]

First problem is an over-powered recoil spring.

 

[GymB]

Second problem (actually the original problem) is an inadequately staked ejector.

Oh crap, this is wrong. Thinking.

 

[John Travis]

First problem is an over-powered recoil spring.

The builder is sorta known for overspringing the slide a bit. More than that I will not say.

In any case, the spring wasn't the cause of the pistol's shenanigans. It would've done it regardless.

Since this one doesn't seem to be gaining much traction, I'll leave it for a while longer and reveal the mysteries.

 

[GymB]

Give it some time, folks are working.

The theme of all these feeding problems is that if it isn’t the magazine that it’s almost always the extractor. Fair enough, but I don’t know how the empty brass gets pushed down based on the extractor geometry, that’s what got me thinking loose ejector, but that wouldn’t have cause the original feeding problem.

This is the only scenario where you don’t say that you fixed it, and for that reason alone I’d guess that the extractor channel was miscut, but I still don’t know how it would cause the described problem.

 

[Bradman]

What gun? What caliber? What model? Make? I've sent three 1911 style guns back for "rethroating" and they work fine now. Unfortunately, quality control is not the priority anymore.

Edit: Two Springfield Armory 1911's and one Kimber 1911. All work perfectly now, needed to be "completed". Unfortunately, the guys making these guns don't care like they used to. The SA guns were a 1911 10mm high end weapon and an EMP 9mm small framed weapon. The Kimber was a 1911 LE SS and I don't remember the other information. The Kimber was a 45.

 

[John Travis]

Give it some time, folks are working.

I posted it early this morning.

This is the only scenario where you don’t say that you fixed it, and for that reason alone I’d guess that the extractor channel was miscut, but I still don’t know how it would cause the described problem.

Oh, I fixed it. It wasn't all that complicated.

There's only one thing that will lead to Problem 2 and it's most often because somebody went by an internet drawing to correct problem 1. I used to have that drawing saved for posting, but photobucket hijacked my account and is holding my property hostage until I pay them...and that ain't gonna happen. Most people who frequent the gun boards have seen it. I think it's titled "How to properly tune an extractor."

And it's anything BUT proper.

 

[John Travis]

What gun? What caliber? What model? Make?

1911. .45 5-inch. I refuse to answer because the builder isn't here to explain or defend himself. It was a simple oversight on a spec issue.

 

[Bradman]

1911. .45 5-inch. I refuse to answer because the builder isn't here to explain or defend himself. It was a simple oversight on a spec issue.

I'm learning.

 

[wvsig]

I am going to guess the extractor hooks were long and that the profile of the extractor was wrong. Most likely from the factory that way. The owner attempted to correct this and took too much off. If I am thinking of the right image it talked about how to "bevel" the hooks and tension the extractor to get better feeding. My WAG is that with too much "bevel" added by the owner the gun. It is only happening on the last round because prior the last round the bullets are being push up by the remaining rounds allowing the gun to push feed vs control feed, if those are the right terms. Once the mag is down to one round the round is jumping out and not getting far enough into the chamber to push feed and then the force of the slide is pushing it back into the mag.

It seems like when the last round stove pipes or does not feed right people go to extractor tension. If that does not fix it then they say bevel or profile the extractor and most people don't know what that means but do it anyway.

This is just a guess because I am more of a shooter than a tinkerer.

 

[John Travis]

I am going to guess...that the profile of the extractor was wrong

Pretty warm there.

Let me see if I can get this picture to post. Then. I'll go ahead and tell what happened to this pistol.

There it is! Remember this drawing and refer back to it later.

 

[John Travis]

Since this one seems to have everybody fairly well stumped, I'll go ahead and tell the story.

The original problem with go to/return to battery was a simple matter of a little too much extractor deflection. The guy knew enough to recognize that, but he'd also seen the above drawing and decided to try to correct the deflection problem by cutting a bevel on the bottom of the tensioning wall. Now, that can be used to create a camming surface to spring the extractor open more gradually when there's a LITTLE too much deflection. A little. And it works pretty well most of the time. The problem is that it's become a default modification and is done to an extractor even if the deflection is perfect.

The problem with the drawing is that it shows a bevel that's way YONDER too heavy and too far up into the wall.

So, this guy starts slow and cuts a little bevel and his problem gets a little better. So, he cuts a little more and it gets a little better but the pistol is still failing to go to battery sometimes...so he goes for broke and cuts that bevel to look like the one in the drawing...and everything went to hell from there. He called a friend who gave him my phone number aznd I spent a few minutes with the gun and was barely able to make the adjustments to the extractor and get it working. Barely.

Measuring showed that the original wall provided .021 inch of deflection which would have been simple and easy to address if he just hadn't seen that damned drawing. So, I cut .010 inch out the the wall and in so doing, a good bit of the bevel turned back into flat wall. From there, it was a simple matter of adjusting the claw to wall dimension and breaking the corners. I could have taken a little more and restored the whole wall, then cut a little from the front pad to set the deflection, but I was afraid that it would weaken the front of the extractor too much and lead to an outright failure.

The last round failure to eject and crushed case happened because the extractor was dropping the case, and...not having a convex surface under it to hold it up...got dragged partway back into the magazine.

How did an extractor that had good tension manage to drop a case?

Because he didn't think about one simple function of the gun and how it could affect the vertical location of a case under the extractor.

When the barrel drops, the case drops with it. If the tangent line of the rim comes out from under what's left of the tensioning wall, it may as well not have any tension. That case will fall to the magazine feed lips...and because the claw still has a bite on the rim...it gets stuffed back into the magazine. The case then angles up, the claw loses its grip, the slide keeps moving, the depressed follower can't actuate the slidestop, and the slide runs forward. Crunch.

Little things. It;s the little things that are out to get us.

 

[John Travis]

Let's see if this one will load.

This illustrates excessive deflection. Here, there's about twice as much of the wall showing as there needs to be. If we assume that the claw to wall dimension is .035 inch, there's about .025 inch of wall in the breech area. It looks like somebody has already started trying to correct the problem by beveling or radiusing the bottom of the wall.

 

[MacEntyre]

Most interesting... I didn't have time to think about it this morning, but I did figure that it started where the other one left off, with an extractor having excessive deflection. I just couldn't imagine how the extractor could send the spent casing into the mag again! Makes perfect sense now.

 

[John Travis]

I just couldn't imagine how the extractor could send the spent casing into the mag again!

Here's a picture of it. Slide locked back manually for a better view.

This is a different pistol. The extractor was clocking badly on this one. Couldn't be fixed. The channel in the slide was mislocated.