How to tell if FXO magazine is authentic?
 

I found an FXO marked magazine with a black plastic bottom in a large bin in a local shop. It was in excellent condition, so good that I wondered if it was authentic or a reproduction. What should I look for? What years or makes would this be correct for?

Thanks in advance.

Hi Captain! These magazines are marked with an "fxo", two eagle-over-37 Waffenamt Marks and a "P.08" on the same side of the magazine. The plastic bottom is fastened to the tube by one blue pin going through the center of the plastic portion. These are very difficult to replicate.