>>> Which [the P90], of course, is illegal for any US citizen to buy or possess. Only military and law enforcement may own them.
Where are you getting that? In certain states, maybe, but not by federal law. The feds will even OK your adding a full-auto happy button, as long as you jump through the paperwork hoops & pay the NFA fee.
I think that manufacturers pistol which uses the same ammo (whose model name I forget at the mo) is no longer in production and likely banned from current import to the US, but not illegal to own.
Hmmm, I was under the impression that NFA compliance allowed for the alteration of the trigger group/lower receiver to full auto, for those with the wherewithall to do so.
I can’t decide whether I like the P90. I handled one (semi-auto) at the last gunshow, was tempted, but had to get the top of my shopping list accomplished. It struck me that surely the ammo is expensive and sometimes a chore to find.