[ithacaartist]

Welcome to the forum, Johnny, you did just fine, right out of the gate!

The mag is probably an FXO, of WWII vintage, and its aluminum, centrally-pinned bottom is absolutely correct. These are among the best performing mags made and worth around a couple hundred if in good shape. Since it is not period correct to your gun, you could sell it and offset the purchase price even more, if you prefer to put the two hundred into a couple of Mec Gar mags and the rest into your pocket.

I'm not sure what your variety of stampings means, exactly, but the markings guys will join the fray here eventually, so I look forward to what they might have to say.

I think I recognize the reproduction grips, as made by a concern in Illinois, IIRC. But I'm spacing on their name right now...

I also have a 1917 DWM that started life as an Arty, but is additionally property-stamped 1920.