I have a vague recollection of some very anal Schuetzen types loading .22RF cartridges with black powder. Maybe they used 4f. I also seem to recall that some folks have fooled with duplex loads of 4f under a main charge of coarser black powder. All this subject to a very dim memory, due in large part to a general lack of interest in such esoteria.

Paul

Stupidity has its way, while its cousin, evil, runs rampant.