Haven't noticed anything "wild" with the .222, 22hornet, 30-06, or even the .308. Did run into the tradtional pressue signs (flattend primer, sticky extractor, etc.) with a 22/250 and a .243. Wasn't every shot, was intermittent, but i wasn't going to push my luck and ceased fire. Only thing they have in common is a fat case abruptly leading to tiny neck.

Everything past that observation is just a guess. Black doesn't "flow" well, it's all jagged easily compressed bits, so suspect it really can't handle sharper shouldered/small bore caees weill...tends to jame up at the neck. Black tends to burn faster/cleaner with more compression, so my suposition is that in a steep bolttle necked case, it tends to block...really compress as the powder burns from behind...and increase in burn rate.

With pistol rounds, the .45acp can actually function until fouled with BP...the 9mm or 40 can't. Use to be a film (do not know if it made it on line,,,was back in teh early days of W. Bell) of a .45 MAC 10 being fired full auto with a magazine full of BP .45acp rounds. Foules a 1911 like you've never seen before, a COMPLETE dissassembly will be required.