Seeking Guidance On Adjusting Galil Gas For Suppression

[Jefferson1826]

After receiving an Omega 300 from the BOGO, I wanted to try it on my Galil Ace Gen II 7.62x39 with 8.3” barrel. Folks online seemed to really talk up the KNS piston so I installed one of those. The trouble is I can’t seem to find a number of clicks where the gun cycles reliably both suppressed and not.

The Omega is currently in for warranty repair so I haven’t done a test in some time but as it is I have the piston open one click and the cycle is fine without a can; much more than this and failure will occur. If I was to thread on the can I would have a few successful shots but eventually a stoppage and a bent round beached between the bolt and the chamber.

On my last attempt I opened three or four clicks and the suppressor gave me no trouble; but once it came off there wasn’t enough gas to run.

I also suppress my AR, SP5, Glocks and a Mac 10 with no worries. What am I doing wrong with my Galil? Is my aim to have it run reliably suppressed and unsuppressed without adjusting the gas a futile endeavor?

Ammo used is Norma, Focchi and Belom.

Who knows when my Omega will be back from warranty repair so I have time to research. Thanks 👍

 

[Deerhurst]

First you need to figure out why it's causing a stoppage. AKs are generally over gassed for reliability. Yous sounds like it isn't with so few clicks of adjustment needed before it's stops running.


I'm not sure what you mean by beached. You'll need to figure out what is making it fail and describe it better for us.

I use the KNS in an AKS74U. Works great! That little gun has almost zero dwell time so it's easy to make it under gassed. I gotta be fully closed without a can.

 

[Jefferson1826]

It’s a bolt-over-round failure to feed, resulting in a round with a rather bent casing.

 

[Deerhurst]

Sounds like either a weak magazine spring or short stroke.

Easiest is to try another mag.

 

[Kalashnikev]

Super simple stuff:

1) You're not "adjusting the gas" with a KNS piston, you're backing off the piston face so the gas is at a lower pressure when it interacts with the face. The volume and pressure of gas is exactly the same, every single time, because the port size doesn't change and the venting/bleed-off doesn't change.

2) Running suppressed shortens the cycle time, because there is more pressure. This is why cyclic rates go up. This is why you are getting a bolt-over-base malfunction- the action is working faster than your magazine spring (see: M249). Your malfunction is called a bolt-over-base malfunction.

3) You're not likely going to find a single magic setting like a DGI .300 BLK AR-pattern weapon. This is why .300 BLK is a magic trick- it met every single ambitious design parameter specified. Pistol length gas is part of what enables that. There is no special short gas + short barrel + Super/ Sub selectable 7.62x39mm ammunition in existence like there is for .300 BLK... which is right there on the shelf.

Check out the recent 9-Hole Reviews Galil Short ACE vid for an actual gas adjustable Galil.

 

[Jefferson1826]

As I’ve waited for my Omega recall repair I’ve come to accept the idea that there will be no ‘do-all’ setting for this Galil, in which case I will add two or three clicks and run suppressed all the time; making adjustments wouldn’t be such an imposition if the piston could be easily actuated without removing the dust cover.

As for how this piston works; there is a clear vent hole opening and closing as clicks are added or subtracted. So there is bleed off, right? The pressure and volume that meet the piston face are indeed the same but once the action opens that gas is escaping through that triangular hole, at which point there is less pressure acting on the bolt as it hits the buffer.

It has occurred to me to do a 300 BLK build and avoid all of this trouble with bent rounds.

 

[Deerhurst]

IMHO, best bet is make it cycle without the can and just use that if you need it to run without a can.

Pressure and volume that the piston face sees is not the same. Volume is greater due to the hole in the center and thus pressure is lower. I have a similar issue with my AKSU. Slightly under gassed with the KNS and no can. Only change is the KNS.

I don't see how 300blk would help.

 

[Jefferson1826]

What it reduces to is this naive shooter thought it would be as easy to suppress this Galil with no adjustments between ‘no-can’ and ‘can’ as it is with every other firearm he owns. If that’s not realistic I’ll move on from finding that sweet spot.

The Omega 300, which is now back from recall, was free so at least I didn’t buy it specifically for this purpose.

 

[Gaffshot]

Send it to a good AK smith like SOF Defense

 

[Slowmo]

What it reduces to is this naive shooter thought it would be as easy to suppress this Galil with no adjustments between ‘no-can’ and ‘can’ as it is with every other firearm he owns. If that’s not realistic I’ll move on from finding that sweet spot.

The Omega 300, which is now back from recall, was free so at least I didn’t buy it specifically for this purpose.

A low-backpressure suppressor would help achieve your goal. The challenge you are facing is to tune for two different functional conditions with a single setting. The further apart those two functional conditions are, the harder it is and the more of a compromise you are forced to make. A higher back-pressure suppressor makes those two functional conditions more different, while a low back-pressure suppressor makes those two functional conditions less different.

Imagine your rifle operates best at made-up setting 1 unsuppressed, but your high back-pressure suppressor would work best at made-up setting 10. You can split the baby and go with made-up setting 5, but you aren't particularly well dialed-in for either condition.

However, a low back-pressure suppressor may work best at made-up setting 3. Now if you set your rifle on made-up setting 2, you are much closer to being optimized for both conditions. It's all about decreasing the size of the envelope you are tuning for.