M305 gas system loose...

S

spirit

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Hello every body...

I have some doubt about my M305 gas system... It loose around the barrel. When I grab the gun by the gas collector and shake it, It move. I can even hear it (tick tick tick...) Is it normal? The lock part is very tight. It act like there is a tolerance error around the barrel.

Is it normal? On my other riffles the gas collector is always tight...

Thank You for your Help...

PS: I appologize for my bad english...
 
Sounds like it need to be shimmed.

Other possible fix is to remove the flash hider and the gas lock and try reversing the lock and tightening it again. Sometimes the threads are more appropriate when facing the other way.
 
If the gas cylinder is loose and the gas lock is tight I'd check the Op Rod Guide to see if this is loose. If so, you can peen and lock-tite it into place. Also, you may want to try peening the splines onto which the gas cylinder fits.

The gas system should be tight.
 
Peen the edges of the TOP gas assembly splineway on barrel
You are trying to make the splineway tighter by rolling the edges over with the punch
3 punch marks down each side of splineway should do it.
Then seat gas cylinder.
This a fairly standard procedure for eliminating side to side (rotational) play in gas cylinder
Fore and aft play is eliminated with shimming or peening gas band shoulder, and or, flipping over gas lock
 
45ACPKING said:
Peen the edges of the TOP gas assembly splineway on barrel
You are trying to make the splineway tighter by rolling the edges over with the punch
3 punch marks down each side of splineway should do it.
Then seat gas cylinder.
This a fairly standard procedure for eliminating side to side (rotational) play in gas cylinder
Fore and aft play is eliminated with shimming or peening gas band shoulder, and or, flipping over gas lock
Click to expand...

What happens if you peen the edges of the bottom?
 
Dling said:
What happens if you peen the edges of the bottom?
Click to expand...

Generally peening the top splineway edges inward is all that is needed to eliminate any rotational play. Peening all 3 splineways could give you a lot of grief installing the cylinder. Most of the recognized literature out there also points to Top splineway peening only. Same goes for flash hider fitting.

All that aside, I have peened in all 3 splineways on some of the rifles I've worked on.
This was done to ensure gas cylinder was rotated slightly one way to optimize gas port alignment and or flash hider "index"

Now if the barrel diameter at gas port is under size or gas cylinder mounting "rings" are tooo large in diameter and giving you a "loose gas system", that can't be solved by any peening so all of the above wouldn't apply. In that case, either a new barrel or gas system that fit each other correctly.
 
Thank You everybody!

The gas system do more than rotating. It also shake side to side. And up and down.

I think gas cylinder mounting "rings" are tooo large (like 45ACPKING said... ) :(

Changing canon and gas system for new one is too expensive for me now.
 
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