I believe that one can reload steel cases: In a reloading manual i have somewhere they say it's a tad difficult, but do-able. The primers may or may not be berdan for the wolf: I know for some calibers built by the american market (.45ACP, .40S&W) that they use boxers, i guess it's because it's not worth the effort to redesign a case never made for berdan primers from boxer to berdan even if it is likely possible, as 9mms exist in both flavors. Berdan doesn't mean it's unreloadable, just harder to do. Aluminium, like blazers, apparently can't be reloaded because they tend to split.
Probably best to just buy: m1 carbine ammo can still be had out there for decent prices, either wolf or aguila. Just never buy something unjacketed from aguila. Their lead .32's and .22's are nasty to clean up after. Their copper coated .22's never give me problems on clean up though.
Oh, and finally, SPG has problematic customer relations. If they get your home address, they will inundate you with magazines full of worthless junk.