Montana Vintage Arms?
Nope. MVA started out making sights from BPCR competition dunno what the founder Jim Geir did before he got into BPCR shooting. So its possible but not likely. But the Long lock kinda dates it. But I still have one Roller Hawken set trigger from the 70s, one of a pair I bought about 10 years ago off a gun show table.So when the lock was used I could not say.