I have a "home made" Red 9. Bolo Mauser, made (as best I can tell) in the 20s. The gun looks like new, so at some time it was refinished, but expertly done. It is also in 9mm Luger, although I don't know who or when this was done.
When I ran across a set of Red 9 grips (that fit my frame) I put them on, to tell ME it was a 9mm. Plus, they look cool. So does the gun, and the shoulder stock/holster.
It is, however, the most unpleasant to shoot handgun I have ever had. Fun as a carbine, although a bit wobbly (you can compensate for this, easily enough), but as a handgun, I would highly recommend wearing at least a thin glove, or something to protect the palm and web on your hand!
That particular gun, stock, a separate holster, manual and some clips are on a friends table at a show, right now. IF someone wants it, they can have it, and no attempt will be made by me or my friend to represent it as anything other than what it is. No collector would be fooled for a minute, and the combination of finish and the asking price will tell anyone who has looked at Broomhandles at all that its a refinished gun with repo stock.
I mean, really, half the price of an original with almost no finish and a shot out barrel ought to be a clear tip off that its not a rare collectible, other than it being a Broomhandle.
All else being equal (and it almost never is) bigger bullets tend to work better.