Gas Lock Position

[froster]

What is the real story on the timing of the gas cylinder lock? Does it need to be tight when the cylinder is all the way back to line up the ports in the cylinder? The lock can not get more than half a turn out of position when tight, so is 0.02" too much ? It seems to me that if the lock tightens 135 degrees past the meeting point with the cylinder then it is only pulling the cylinder about 0.012 forward when they are secured in alignment. How many people end up using various techniques to push the cylinder all the way back when in use?

 

[TSMGguy]

First of all, is your rifle all GI? There can be considerable variations in tolerances in the civilian market guns. The lock should rotate slightly past the installed position, but I've never seen much over 30 degrees with an all GI set up. 135 degrees certainly seems excessive.

 

With everything assembled, how does the gun shoot? Any problems?

[froster]

Yes, it's all GI, including the barrel. This is the second lock nut I've tried with the same problem. Functioning is fine with or without a spacer between lock and cylinder. I was wondering what is the latest thinking on the subject. It's a Winchester barrel and I've noticed that the barrel gas port is somewhat smaller than those on many types of auto guns, so that maybe some of the barrel port could be blocked by the cylinder.

What do you think of cutting and rewelding the lock so that it will be tight on top and aligned at the bottom?

[TSMGguy]

The gas hole only appears small because of the great pressures involved in actuation. A larger hole is not needed.

 

If your gas cylinder splines are tight on the barrel and the rilfe is reliable, I would not mess with it in any way.

[Bridgeport28A1]

The USGI M14's I maintain tend to have the lock go past the gas cyliner 30-40 degrees or less. I never recall having one go past 45 degrees on the 200 rifles or so our department has.