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Discussion Starter · #1 ·
My Yugo is having occasional FTF problems and I am looking for hints to fix it. The problem seems to happen only once every 20 rounds or so, and there is no obvious pattern. It has happened with Golden Tiger FMJ, S&B FMJ, and Wolf HP ammo. My first thought was the gas system; when I took the gas tube off, I noticed the piston was really loose and fell right out. Bought a replacement piston and, even though it fit tightly when first installed, it, too, is now loose (much looser than my other rifles). Ran a pipe cleaner down the gas port, no issues there. It does seem that the fit of the gas tube to the front bracket is a little loose but I don't see any obvious signs of gas leakage. Rifle is properly lubed.

Am I missing anything?? Thanks
 

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Since short-stroking can result from various causes, there are few things to consider:

1)The piston falling out of the tube isn't a test of improper fit. A vacuum gravity test is the best way to determing if the piston is too loose and possibly letting excess gas past the piston head:

With the thumb covering the tube opening, turn the assembly to a vertical position. The piston should fall slowly in the tube with noticeable suction on against the thumb.

2) You wrote 'FTF' (failure to Fire). Did you mean "FTE" (failure to Eject)? FTF would be an ammo or trigger/bolt related issue.

3) If you meant FTE, how was case ejection prior to the FTE? Robust, unobstructed Ejections should be throwing spent cases 10-20 feet.

4) Aftermarket recoil buffers have been attributed to recoil issues.

5) Have you checked the piston extension and spring for unusual wear?

6) Loose fit of the piston can often be free play between the tube bracket and the wooded handguard. As long as the piston tube locks is tight forward and aft, that free play shouldn't be a problem.

7) Recoil spring is properly installed. Curly end forward?

8) Cosmoline in the chamber can hinder case extraction . As the rifle heats up pockets of grease will adhere to the cases (especially lacquered steel).
 

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Discussion Starter · #3 ·
Thanks for the tips; I did try the vacuum test and it seemed to work ok.

What I mean by "FTF" is "failure to feed". The spent casings eject with no problem, but occasionally the tip of the fresh round hangs up on the chamber lip. I wondered if that was a short stroking problem caused by a gas leak.

The gun is not all matching; the gas tube/handguard is a replacement, and there appears to be a little excessive "wiggle room" where the front of the gas tube meets the forward bracket. A more careful inspection this afternoon showed some carbon residue on the barrel near that junction.
 

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Ahhh.

Sounds like this is not a gas related problem-- especially if case ejection is up to standard.

Could be a magazine Problem. I'm not personally familiar with magazine feed issues, have only read of others having similar problems. The SKS magazine staggers each round (left and right)-- do you know if it's a left or right side round that gets caught? Also helpful to know if which round out of 10 that fails to feed (1st to Last).

There are a lot of folks here who'll be able to help you with a little more info on the nature of the problem. Pictures of the jammed round, of the empty mag and receiver well will be helpful too.

Good luck.
 

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Buy or make some dummy rounds (set a bullet in a fired case and paint it orange with day-glo nail polish so you don't fool yourself) to look closely at feed and cartridge position as you hand cycle. Don't try that with live rounds as a slam-fire or trigger slip could spoil your whole day.

Check your mag spring and recoil spring to be sure they are pushing up hard and look very closely at dummy cartridge position after each cycling by hand and later by live fire.

My guess is the cartridges are not in position, perhaps from a bad spring, mag lip, or even a bent mag as the full ejection seems like the stroke back is OK but return loading is not.
 
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