Taurus CT9 - Brazilian UMP

The CT9 is a lolhueg blowback 9mm carbine based on the Brazilian MT9 submachine gun. It's huge, it's missing a bunch of features to make it import compliant, and did I mention it's huge?

This blowback 9mm is significantly larger and heavier than a carbine AR. The upshot is, it shoots really well! The CT9 is also fully ambidextrous, with ambi safety lever, bolt release, a paddle magazine release, and a swappable non-reciprocating bolt handle.

Taurus factory magazines are rare and expensive, and only hold 10 rounds (they're 15 rounders with stampings to limit capacity for import). The magazine pattern is similar to Colt 9mm SMG magazines, which can be modified to fit the CT9 giving you 32 rounds.

I've also seen forum posts indicating you can modify AR grips and AK folding stocks to fit the CT9, but it takes a bit of drilling and filing.