Troubleshoot Thursday!

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John Travis

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Dec 22, 2016
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Location
Lexington, NC or thereabouts.
Timeline: 1980something...probably '88-'89. Memory fails me.

Subject: Original/correct 1943 Ithaca USGI newly purhased through an out of state dealer, sight unseen.

Issue: Short recoil.

Clues: When hand cycled slowly the only indication of a problem was a very slight catch...more of a bump...at roughly 1/4 inch of rearward travel. There was also a slight hitch as the slide went to battery, less pronounced than coming out.

The slide wasn't oversprung, and there were no issues with the disconnect or sear spring.

When firing, the slide would stop short and return to battery with the fired case remaining in the chamber until hand cycled, which revealed a little increase in the "bump" noted earlier.

Disassembly revealed the problem, which required a part change to get it running. Close inspection suggested that the pistol hadn't been fired more than a few times in this condition, so any damage to slide and barrel was minimal, and because the owner didn't plan to fire it more than a few rounds a year on his late father's birthday, there was no immediate need to replace anything else.

Go!
 
Bent slide stop?
Added like others: Link.

Added the link as I thought that was deemed as good. I agree with others.
(Probablystill wrong)
 
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Hmmm... link or firing pin stop? Link out of spec would not be fixed with a part change. Bent slide stop is a good thought. Not much else gets in the way of the slide.
 
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I think it’s a long link.

but why does it not eject? Hmmm
 
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I would have at first guessed too heavy a spring…. But maybe instead a spring that’s too long or some kind of shock-buff installed?
 
Catfish said:
I think it’s a long link.

but why does it not eject?
Click to expand...

Bingo!
Typical of many GI pistols, the barrel would drop a tiny bit when pressed with the slide in battery. Though the condition does no harm, it's of great concern to some...so Bubba long linked the barrel in order to tighten it up. The problem was that he used the longest link he could find.

The reason that it didn't eject is because it couldn't.

When fired, the barrel was moving rearward too fast for the lugs to get clear of the slide's lugs and when the barrel struck the vertical impact surface with the lugs still vertically engaged, it stopped the slide cold at 1/4th inch of travel. Slowly hand cycling gave it a gravity assist.

Ordinarily, I'd have advised the owner to replace the barrel because one such crash would pretty much guarantee a sheared lower lug within a couple thousand rounds, but because it was an original and because he didn't plan to shoot it very much, I gave my go-ahead with a caveat to keep an eye on it. Luckily, the locking lugs...slide and barrel...were only slightly deformed, and headspace was within allowable limits.

The hell of it was that, with the proper link, the barrel didn't drop more than about .005 inch when pressed hard, so the "problem" that Bubba fixed was a non-starter.
 
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John Travis said:
When fired, the barrel was moving rearward too fast for the lugs to get clear of the slide's lugs and when the barrel struck the vertical impact surface with the lugs still vertically engaged, it stopped the slide cold at 1/4th inch of travel. Slowly hand cycling gave it a gravity assist.
Click to expand...
That is truly fascinating...
 
MacEntyre said:
That is truly fascinating...
Click to expand...
The link not only pulls the barrel out of the slide, it times the function. A link that's too long delays the linkdown process and can't pull the barrel down far enough to completely disengage from the slide. At full operational speed, gravity doesn't have time for the barrel to drop.

With a link that's just a little too long, we see lug corners rounded off because the barrel is almost-but-not-quite disengaged, and the gun seems to be functioning fine. With this one, that condition occurred during hand cycling, which explains the slight hitch when the slide was moved backward.

The hitch going TO battery was happening because the barrel was moving up too early and too quickly due to the pole vault effect of the long link...and the lugs were hitting as they tried to enter the slide's lugs before the slide was in position to take them. This also happens when a bullet nose hits too low on the barrel ramp, pushing the barrel forward and up too soon in relation to the slide's position.
 
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MacEntyre said:
I thought the bullet was supposed to jump over the barrel ramp..
Click to expand...

It is. Sometimes it doesn't. Like, when Bubba has polished the feed ramp until the top corner has rounded off...or when the 32nd inch gap is less than spec...or when the feed ramp angle is more than 31.5 degrees...or when the barrel ramp angle is less than 32 degrees.

That's when it winds up on my bench like that Commander of yours did all those years ago.
 
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