How tight should the gas lock be?

autocrash

autocrash

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Hey Guys,

My new M-14s arrived in the mail yesterday!! :runaway:

Stripped it last night, cleaned all the cosmo off, greased it up (missed a few spots... oh horror, will have to take it apart again tonight! :D)

Anyway, after a once over, everything looks good, a little play in the oprod guide (I can feel it move, but not see it move) and it lines up pretty well with the gas piston, so no complaint there...

BUT the gas lock... If i snug it down it stops at about 1/6 of a turn away from lining up... which means I need to back it off by 5/6 of a turn in order to get the gas plug in (leaving a large enough gap between gas cylinder and lock that I can see light through).

So... how tight should the gas lock be? Should it require tools to get it tight (this has all been by hand so far) (ie. Gas lock wrench?). Should I take some emery cloth and polish off the back surface of the gas lock, so I can tighten it up by hand? Or should I look at shimming?

Any help appreciated!

Matt
 
Try flipping the lock over and see if that helps. Allen wrench and castle nut pliers are useful for removing the flash hider.
It would be ideal if it hand snugged up at about four thirty or five o'clock. While supporting the gas cylinder and barrel gently tap to six o'clock with a plastic headed hammer or wrench.There are shim kits available from Marstar.
Next time there's a Hungry clinic in your area, sign up. They're a lot of fun and you learn stuff.
If I'm off the mark with the info someone will be sure to chime in.

autocrash said:
Hey Guys,

My new M-14s arrived in the mail yesterday!! :runaway:

Stripped it last night, cleaned all the cosmo off, greased it up (missed a few spots... oh horror, will have to take it apart again tonight! :D)

Anyway, after a once over, everything looks good, a little play in the oprod guide (I can feel it move, but not see it move) and it lines up pretty well with the gas piston, so no complaint there...

BUT the gas lock... If i snug it down it stops at about 1/6 of a turn away from lining up... which means I need to back it off by 5/6 of a turn in order to get the gas plug in (leaving a large enough gap between gas cylinder and lock that I can see light through).

So... how tight should the gas lock be? Should it require tools to get it tight (this has all been by hand so far) (ie. Gas lock wrench?). Should I take some emery cloth and polish off the back surface of the gas lock, so I can tighten it up by hand? Or should I look at shimming?

Any help appreciated!

Matt
Click to expand...
 
x2 on above post , try and take off the flash eliminator and if you are lucky it wont be spot welded on.If it is you can support the barrel and use a punch and a Hammer to get it off...see the stickies on this.
Once you get the flash eliminator off the rest is easy..add a shim ....it should get snug about the 5 oclock position and get tapped into position with a rubber hammer
 
chalkriver said:
....it should get snug about the 5 oclock position and get tapped into position with a rubber hammer
Click to expand...


See, this is what I was asking... right now it's snug at about 4 oclock... and that is only by hand, if I give it a smack with a rubber mallet, that should get it tightened up properly...

I think anyway...


Thanks guys!

(oh, also, is there any ghetto alternative to the castle nut pliers?)
 
yea, you need one of those vise grips that "look wierd" and a grinder- you grind the lips down to fit in the spaces of the castle nut- there's a sticky on that somewhere
 
That is the way you want it to be...use a rubber hammer to tap it into position or a gas lock wrench .....if you have a friend who has a gas lock wrench trace it out and cut one for yourself out of the white plastic cutting boards.

I lost my pattern before I could make my own :mad:
 
M14 FAQ Sticky said:
The lock should be snug at 4 o'clock so when turned to 6 o'clock, it securely clamps the loose front band.
Click to expand...

Well, I guess I should RTFM more... ;)

I like the idea of a gas lock wrench made out of a cutting board... may have to look into that. As far as a pattern, well, it's two circles... I think i can wing it... (I bet the USGI specs are on milsurps)

Thanks again guys...

I guess now I have a date with a rubber mallet and grease.... wait, does that sound dirty?

Matt
 
The gas lock has no bearing on piston movement (?). If the gas lock is not perfectly aligned, the plug won't go in. You might be talking about the gas VALVE.

As for the lock, for ideal match shooting, you want it to *just* align with very heavy finger pressure or light pressure with a gas lock wrench.

Try flipping it around first. That sometimes brings you into alignment, believe it or not. If not, pick whichever orientation brings you closest to lockup and apply shims.

If you don't want to remove the flash hider, then cut a slit in your shim and force it over the barrel. Just remember to check whenever you strip the gas system for cleaning that your shim doesn't slip out of place.
 
matty86suk said:
sure it does, i bought a glfs from marstar and it was super tight when lined up properly, quess what, piston was binding, theres a simple solution to this problem.....
Click to expand...

Umm... I'd have to see that to believe it. The piston does not travel as far forward as the gas lock, it bottoms out o nthe base of the gas plug, which sits further into the gas cylinder than the width of the gas lock.

All the gas lock does is keep the gas system from moving forward on the barrel under recoil.
 
Claven2 said:
Umm... I'd have to see that to believe it. The piston does not travel as far forward as the gas lock, it bottoms out o nthe base of the gas plug, which sits further into the gas cylinder than the width of the gas lock.

All the gas lock does is keep the gas system from moving forward on the barrel under recoil.
Click to expand...

when too tight(i belive) the whole cyl. assembly is torqued and in turn the piston binds, i couldn't figure it out at first either, to fix it, which could help lots of GL tightness problems was...i filed/faced the gas lock using a fine file until the desired tightness was acheived, some what tetious but it worked good...this way the gas hole lined up perfectly, put now the plug is too deep(by a few thou) in the cyl. but this hasn't affected function, and i can't find any info on how deep the plug should go into the cyl....
 
matty86suk said:
when too tight(i belive) the whole cyl. assembly is torqued and in turn the piston binds, i couldn't figure it out at first either, to fix it, which could help lots of GL tightness problems was...i filed/faced the gas lock using a fine file until the desired tightness was acheived, some what tetious but it worked good...this way the gas hole lined up perfectly, put now the plug is too deep(by a few thou) in the cyl. but this hasn't affected function, and i can't find any info on how deep the plug should go into the cyl....
Click to expand...

I don't think it's even possible on an in-spec gas cylinder and barrel mating to torque the whole cylinder enough to bind a piston - it is held in place by splines in the barrel and the casting is stronger (to prevent torsional warping) than you are ever going to be able to counter-act by torquing of the gas lock.

I didn't see your rifle and can't comment on it specifically, but if your piston was binding, it is FAR more likely that either your vent was plugged or you had some grit or a foreign object causing friction between the cylinder and piston.

I wouldn't recommend people file the gas lock to get alignment. The thickness dimension is somewhat important in setting plug depth. A far better solution is a standard shim job between the cylinder and the barrel shoulder. If it's a gas lock sight, good luck filing one - they are harder than most files.
 
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