...then I found what I was looking for. Arsenal Firearms makes the LRC-2 Conversion Kit for their Strike One pistols. It comes with an 11.8" long barrel to really boost the velocity over the typical 4-ish inches, and it comes with a nice light folding stock, or an M4-type telescoping stock. They could just as easily be made with a brace like non-NFA Micro RONIs. If someone made a conversion kit like that for Glocks with a longer barrel (not necessarily that long) instead of just an extended barrel shroud like the Micro RONI, I think it would be worth buying.