YoungestPiperCub is still incorrect. The proprietary Receiver contours used on the BR10 series of rifles will not interchange nor mate up with Ă ny modern AR10 Receivers, neither the Lower nor the Upper. This has been repeatedly afffirmed by Brownells. The only receivers which might interchange are the original AR10 components, however that remains to be seen. For that reason, the BRN10 with an 18.6" Barrel stands a very good chance of being classified as Non--Restricted in Canada once submitted by Wolverine Supplies and procesed by the Lab.