priming powder should be used to prime flintlocks only.......i have over hlaf a pound i was given last year....shot over a pound of 2f since and barely used any priming powder...it was given to me by a guy that taught me to shoot hte flinter....he said he doesnt shoot his flinter much anymore and if he needs it he knows where i live and can get some......he had it for a LOOOONG time...the cans arent even the same anymore.....keep the lid on and keep it in a cool dry place and itll last forever.....dont have to worry about loosing velocity or anything its for priming......but i dont think you can use it in your main charge....only thing i heard of was putting like 10gr in before 777 or pyrodex to make it go off better in a flinter or something like that......