Loc-tite and gas block

[LRRPF52]

Have they? First I've heard of it in 30 years ('and years').

My opinion is that you should use glue sparingly on AR's. If you are worried about a loose seal, get a tighter fitting block that taps on with a hammer or clamps. If it leaks slightly and the system still functions it's probably a blessing that you're not having to cope with that excess pressure at the receiver. If you think glue on blocks improves accuracy ('for some reason') then I have no counter argument for you here. That one is a non sequitur.

Sorry mate but I have to call it when I see it. I won't lose any sleep if you want to use glue on your block seal or advise others accordingly but the only glue on my guns are gas block screws and sometimes handguard screws.

AA did testing across a large fleet of rifles, and found that after Loc-titing the gas blocks, accuracy tightened up measurably. It's been addressed here before in detail. My initial guess was some type of resonant harmonics with the block, but it may be about maintaining a consistent gas seal as well. I know smiths that hand-fit them as you describe.

I like the idea of what Knight's is doing with their Mod 2 gas system, which is a mechanical seal. The benefits to a sealed gas block, and thus less leakage, is a smaller gas port can be used. Smaller ports help reduce erosion, which is a factor in maintaining a consistent gas pressure signature throughout the life of the rifle. A lot of this work has been done for the 16" 7.62x51 NATO carbines, as they have become more requested by end users, after going from 24", to 20" guns in the SASS or DM role.

Gas porting diameters have been driven by the reality of leakage in the conventional AR gas blocks, and the RDT&E Knight's has done is solid. They have good engineering staff, and the largest collection of Stoner samples in the world to refer to when looking at ways to improve the system. The thing that bothers me about leakage is that it can spiral out on you when looking at consistency, especially as the leaking gas erodes the path of least resistance between the block and journal, as well as the gas tube.

It also doesn't hurt to have the pressure sealed in the gas block and tube area, and let the BCG deal with it, since there are gas relief ports in the bolt carrier for the expansion chamber to vent when it needs to. I also find the relief port geometry used by the Dutch interesting, when looking at the Dutch ArmaLite AR10's. Compressed fluid dynamics and the geometry of the components can make big differences in how the gas behaves, when looking at laminar flow.