To Copelc the LK mark with the "R" crown on the FSB is probably Bushmaster assembled parts.Forge Im not sure but im almost 100% sure it came from Bushmaster.I have an FK,BK and keyhole for A2 uppers with the"R" crown on the FSB and a DK A1 with the same"R" crown on the FSB.I know the DK was a diemaco upper that came through Bushmaster.Also Bushmaster uppers are usually grey baked dry lube on the inside does yours have this as well?What is stamped in the top of the barrel past the front sight base?is it BMP 5.56 NATO 1/9 HBAR..if so then definately Bushmaster assembled.They make their own barrels and now machine their BFI marked lowers but everything else I beleive is subcontracted parts.