There are always nay sayers; let's see, 40 years of putting the anti-seize on lug nuts, no failures, no stuck lug nuts either, I did my own auto mechanician most of my life, I did a brake job on my girlfriend's truck a few months ago and found that a 77-year-old guy suffers from getting under a vehicle now so I am DONE with such. 24 years of using it on tractor parts, no failures. At least 15 years of lubing breech plugs, percussion nipple threads and other assorted M/L bolts, no failures. 30 years of working with various crafts, mostly machinists and boilermakers in two 1,2OOMW + coal fired power plants who used it on high pressure bolt threads religiously, no failures.
I think it might be safe to use on a breech plug.