I tried searching but didn't find anything. Under the new proposed ATF rule, what are the options for an MCK* brace for a pistol? (Mine is for an M&P 2.0). Can I register as an SBR attached to one specific pistol? I know I can just get rid of it too. I'll likely sell it as I don't really shoot my M&P's much anymore, but wanted to know my options? thanks! *the MCK is a device that you put a pistol into and it adds a brace.