If they are BBs for an air rifle DO NOT reload them. They are of a harder steel and could mess up your barrel.
Commercial steel shot is pretty hard, but if BB gun projectiles are made the same today as when I wore short pants, they are made from copper or a copper alloy not steel. As such they should be safe enough to push through a smooth bore, but I'm not sure if they have enough mass to pattern very well. Pattern a few and see how they perform and if the idea is worth pursuing.
Not copper anymore just copper plated and two to three times harder than the normal steel shot used in shot guns. Some guys have tried it but I definately would not.
http://www.shotgunworld.com/bbs/viewtopic.php?f=13&t=124343&start=0
Guys shoot tungsten and all types of steel. If your shotgun is modern with an open choke you will be fine. Of more concern is what load data are you planning on using?
Shotgun reloading is touchy, so make sure your load data is appropriate for your components.
IF you actually meant lead BBs, then go for it.



























