ChiefShotguns,
Thank you...about the trigger...that selector is usually the indicator of a Deforney trigger...I was trying to figure out if Deforney supplied them to Masquelier or if in fact the gun was made by Deforney. If you would like to see another Deforney with a single trigger, Thad Scott has a Deforney sidelock O/U for sale right now that has the same barrel selector.
Miller single triggers usually have the selector built into the safety slide. I don't have a copy of the patent to show you but, Gerbruder Merkel Suhler Waffenwerk opened a facility (1920's) in Belgium primarily to supply the gun trade with O/U actions... with their patented Kirsten lock up...now somebody had to buy them...you just don't see Belgian Merkels floating around...post 1930 Merkel began selling patented ejector actions to the Belgian gun trade...so I guess if your gun has a Merkel ejector system, that would offer more evidence one way or the other. I do have a copy of the Belgian Merkel patent ejector system if you would like to see it.

I hate the fact that my records don't match exacly with everyone elses, but I can't just twist them...I certainly can't change the patent records..

Later, I'll review the 10+ Miller trigger designs to see if any of the Miller clan had ever used a barrel selector that looks like Deforney's patented design...

The absence of any Masquelier proprietary touchmarks coupled to the obvious Deforney single trigger is starting to look like perhaps you were given weak information about your gun. The crowned D doesn't auger well for Masquelier being the maker either.