how many shots do you get from a pound of BP.....im shooting 90gr loads most of the time if theres a scientifical mathmatical way to figure it out......just wondering....im going to buy some soon and want enough to last me the season.......my last can i didnt keep track and when i went shooting with my friend to teach me the ropes he actually spilled some..cant remember how much but some was spilled.....thanx alot