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Gas piston question

Printed From: The Carbine Collector's Club
Category: The Club
Forum Name: Safety/ Accuracy/Shooting/Ammunition/Care and Maintenance
Forum Description: What to Check, Reloading, Tips for Accuracy, Competitive/Recreational Shooting
Printed Date: May 29 2023 at 5:12am
Software Version: Web Wiz Forums 12.01 -

Topic: Gas piston question
Posted By: john843
Subject: Gas piston question
Date Posted: May 27 2022 at 8:30pm
I've got a gas piston nut on an NPM shooter that is loose after shooting the rifle several times. It doesn't really back out and the gun has never malfunctioned. I've been snugging it down with a small wood block and brass hobby hammer but after firing it you can flick the nut around with your fingernail.
Didn't know if blue Loctite around the last couple of threads that contact might be an option or maybe a tiny spot of JB Weld in the staking recess (small enough to be removed easily) could work? One thing I know I won't be doing is to attempt to stake it. I have three usable barrels and would like to keep it that way!
Thanks for any suggestions,


Posted By: GotSnlB28
Date Posted: May 27 2022 at 9:05pm
I have used loctite blue and none have come loose in use. Clean/degrease the threads well. The piston wrench works well to snug tighten. That is my advice, there are strong opinions out there for staking I know, and may even follow mine. But I can tell you the blue loctite works well and you'll never see it or risk damaging the gas cylinder however remote that chance is for non-professional stakers.
I wouldn't use JB or epoxy.

Posted By: john843
Date Posted: May 28 2022 at 3:17pm
Thanks Joel, I'll open a new LocTite and give it a try. Before posting, I looked for any old threads relative to piston staking and found one Roger started but it was more to do with the fact that some later carbines were never staked. This one was staked at some point but the nut had been run past it prior to my receiving the rifle.

Thanks Again,

Posted By: W5USMC
Date Posted: May 28 2022 at 3:43pm

USMC Retired
NRA Life Member

Posted By: smtrico
Date Posted: Jun 20 2022 at 4:26pm
Try using the green Loctite instead of the blue.  Last year I bought one of the MidwayUSA carbines.  It had a stuck gas piston, which I got out be removing the piston nut, but then couldn't get it back in.  Took it to a gunsmith as the threads were all fouled up.  He fixed all that and put in a new piston nut.  Anyway, rather than restaking the piston nut, the gunsmith said he always uses the green Loctite.  It is stronger than the blue, but not quite as strong as the red Loctite.  The key, though, is that the green Loctite is formulated specifically to withstand very high heat and so it can handle the heat that is generated when you fire the rifle.  He said the blue Loctite may not last for that reason, but the green will. 

Posted By: john843
Date Posted: Jun 21 2022 at 7:07am
Thanks for the heads up smtrico. I'm going to replace the piston nut on this same rifle with the type 2 (?) nut from Amherst since it already has a type 6 op-slide with the increased dwell and will definitely give the green LocTite a try.

Thanks Again,

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