Odd that "Bushmaster" keeps popping up in this thread.
Last several batches of Bushy M4's we took receipt of ALL had WEAK staking of the gas key screws.
For the Fix.
If the gas key isn't beat up from the thrashing it took while cycling and loose(I have a parts bin that does NOT come from my personal wallet mind you.) they can be tightened back down and re-staked.
The correct torque as mentioned above is 30-40 inch lbs.
However.......
Unless the screws, Key, and carrier are new, and things un-boogered this might not be enough.
Some respected folks in the industy have abandoned the torque limitation altogether, and have gone with "Tighten untill you feel guilty" and then stake.
Use the guidence in the Army or Marine Corp's TM for staking.
The locktite angle sounds good on the surface.
However, Locktite breaks down with heat.
The gas key taps into the hot expanding gasses of propellant combustion.
Even "permanent" Locktite can be overcome by application of heat for disassembly of "Permanent" components.
Stake the thing.
Do it right the first time and forget about it.
As for the torque issue.
Knowing when to stop is a matter of "Feel" for the most part without a torque wrench.
First time "Feel" is often wrong.
Extracting busted screws from a bolt carrier, is a pain in the keester!!!
Follow the TM guidelines unless you are very framilliar with the "Feel" of threads seating.
S-28