SKS vertical stringing

[NSP64]

My yugo spit them vertical when fired semi auto, but not when fired single shot(gas port closed)? Any ideas why?

[chaos]

Does it do this with all types of ammo?

[ra_balke]

Humm...

The only reason I have ever seen for vertical stringing was a variation in the pressure caused by in-consistand burning of the powder charge.

Yur gas port may be causing somthing.. maybe a leak somewhere... ?

[trickyasafox]

could it be the barrel heating up? how long between shots?

[NSP64]

Semi auto slow fire and seems to do it with all loads?

[Tiger]

One does not realize how much pressure there is between piston rod gas block and where rod hits bolt carrier. Also to there are much vibrations. This is long time fight among AR15 people that the DI gas system is much more accurate then gas piston system. Funny though that most Yugos shoot very well. You found your problem that it shoot better with gas turned off go from there for problem.

Ralf

[runfiverun]

vertical stringing is usually caused by velocity variations.
wether by the rifle moving the powder back and forth in the case.
or by the load, not a dense enough load so inconsistent ignition,, also caused
by..... just because that is the nature of that powder.

[MtGun44]

How about this.

Maybe you are raising the muzzle to cycle the bolt by hand and thus
settling the powder to the rear of the case, improving ignition/burn
consistency?

With semi-auto, the powder is pushed to the front when the case
suddenly stops in the chamber.

Just a hypothesis. Now go test it by doing single shot and then shaking
the gun with the muzzle low a couple shakes each time you load a
new round and see if you get your stringing back.

Bill

[NSP64]

The load is 22 gr Imr4895 (full case) and a 180gr cast boolit. powder placement should be good??? more range work due[smilie=b:

[MtGun44]

Hmm. Full case eliminates powder position. How about a faster powder
to lower the port pressure? Maybe you are slamming the action around
with too slow a powder and getting some kind of 'issues' with the action
cycle.

Maybe give 3031 or another faster powder a try?

Bill

[NSP64]

Have tried 4227,2400 and they wouldn't cycle action? where does 3031 fall burn wise?

[MtGun44]

slower than 4227 or 2400 and faster than 4895.

Bill