MW - What they've said. It's almost certainly an SMG loading. Don't get rid of it though - 8K is a significant quantity of "stash". You've already made the investment, now get some value out of it. I too advise against shooting it in an alloy framed pistol. We destroyed "a few" M9s shooting the brown box 9mm (Canadian IIRC) in the late 80s, early 90s. BHPs handle it just fine (and they're relatively inexpensive). RRA also makes a nice AR platform 9mm SMG (probably illegal where you live though
) that'll appreciate the extra "zip".