NOTE: BRS47 Lower receivers will NOT function with Mil-Spec upper receivers as the AK47 magazine will interfere with the upper receiver. To build a BRS47, you will need to use the BRS47 Upper Receiver as it is manufactured to accept the larger AK47 Magazine width.
BRS47 Lowers and uppers also require the use of the BRS47 Bolt Carrier Group. Mil-Spec carriers with a 7.62x39 bolt will NOT work. The Billet Rifle Systems BRS47 BCG is designed and manufactured to work specifically with AK47 magazines.