Stan,
Please find attached details of testing done in February, in Australia by a coating user, where they used the Dark Green HI-TEK coating on alloy 92:6:2.
This may shed some light on what can be done.
Hope it helps with your questions.
165 grain, 309 dia, 308 rifle, maximum load 41 grains ADI powder 2206H , travelling 650-750 ft/sec,
20 shots were fired. Only powder residue left barrel was clean. 2 coats of coating.
One coating also gave same results same. No gas checks were used on one coated or two coated projectiles.
125 grain, 316 diameter, 8 grains 2205 powder, travelling at 1200-1300 ft / sec with 2 coats.
310 Cadet rifle. No gas checks. 65grn 309 diameter Marksman fired at 1700ft/sec with 2 coats.