Gas piston question

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,

John

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,
John

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.