All I use for prime is Goex 4F and have never had any concerns over age of black powder.Ace-Man said:I do not place the open BP can on top of the stove. That would be severely foolish. I do however place it on the mantle above the wood stove where allot of very warm and dry air passes.I've read back in day of folks very carefully placeing the BP in the oven portion of their stoves. The heat from the stove was receding but still hot. This meant for a quick ignition for the next days hunt. I have never attempted this. I have however purchased a super fresh can of FFFF and placed the can inside a food sealer bag and sucked it tight to preserve the powder. Works for me.
But 4F is sensitive to moisture in the air...when hunting I always replace it at least hourly, and if I know the humidity is high that day (or foggy, drizzly, etc) I'll replace it every 30 minutes...it only take a few seconds, costs less than a penny, and so far I've never had a flintlock ignition problem while hunting.