I talked to B&T at Enforce Tac and they said you guys can bring in anything they make.
Is it possible to bring in the Rotex 3 prong adaptor as used by the French Army HK 416 F in both M15X1 ( for HK MR series) and 1/2 x 28 (regular AR thread)?
The one in the picture is M15X1 with the typical HK shoulder.