A lot of places were making up the 28ga M12 conversions after Winchester sold the big lot of parts off in the 70's or 80's. That included the 28gs bbls, mag tubes,carriers, shell stop,ect.
Rumors were that one person had bought the whole lot,,other rumors were to the contrary. Rumors are great sources of information.
Simmons Gun Specialtys were doing the conversions for quite some time. So I quess they had bbls and parts. They still had all the set up to do the conversions as recently as maybe 15yrs ago or so but had run out of bbls.
Jimmy Clark the pistol 'smith used to do them.
(I guess bbls and parts were available from someone/somewhere)
As long as you had either a 20ga or 16ga M12 (same frame) you had what you needed to build on.
16's were most likely cheaper to buy to use as a starter.
I'd guess the surplussed orig Winchester bbl made at the factory and fitted to any old 16 or 20ga M12 would be a giveaway sometimes if the bbl address style on the 28ga bbl from that period didn't match the period of the ser# on the frame it was then fitted to.
Most of these conversions are tastfully reblued. The donor M12 usually a scab gun bought on then cheap. The 28ga Winchester bbl and tube NOS with a nice finish. So the frame & TG in the very least redone if not the whole thing.
...Probably get it with some orig Hang Tags, a Box and orig work order from the Custom Shop.
