No, they only pin/weld 14.5 uppers
It shouldn't be , there isnt much of a reason to pin and weld something that short , you'd need a 6 inch device to meet a 16 inch limit
I don't see why it would. the reason for a pin and weld would be to make the barrel 16 inch in compliance with the nfa. so this would still be shorter that. so why would it be?