i say steel they call it bimetal but basically if a magnet sticks to it for any reason its a no go
not so sure a bimetal case is that big a deal but hey i get it that backstop is not free
so fair enough just wish there were some options as it is really rare to find lead core brass cased
The
case is what holds the powder, has the primer on the back end, and is ejected from the side of the action when you're done. It has no bearing on range permissibility, and is usually brass, but cheap ones can be aluminium, and military surplus is often steel (magnetic).
The projectile is what's plugged in the front of the casing, and is ejected much, much faster from the front of the gun when you pull the trigger. Traditional construction is a lead core in a
copper jacket. If instead it has a steel core or a steel jacket, whether or not it also contains lead or copper elements (bi-metal, copper wash, etc.), it can present problems with damaging low-grade steel range back-stops.
This confusion in terminology is important to point out, and I have known of range officers waving a magnet around a cartridge, and if it sticks anywhere, including the case, it is a ‘dangerous armour-piercing round.’