Stan,
I own my share of Fox guns. Have four of Beckers. For starters the engraving is completely different from what I've seen on Burts guns. I'm talking about the writing on the barrels of course etc. (not the engraving pattern).
Perhaps the biggest question arises from the Mississippi Delta itself. Many men that we would consider "old timers" who hunted with Nash, pigeon shooters who stay under the radar etc. would tell us that the gun ended up elsewhere. PM me if you would like more info.