If you don't want to cut the long metal magazine, or if you don't find the metal short magazine, this one will work like a charm. Modeled 1:1 from the real deal,
it will fit and hold the HFC Mauser C96 / M712 Airsoft Pistol.
It has a tank if you want to add some ballast, which I totally suggest, the metal one is heavy. Just fill it with screws & nuts and add some hot glue.
Don't worry about the internal machinery, it's long enough to hold and release with the eject button, but short enough to respect the gas system.
Here are some tips about painting the Frosted plastic:
https://www.shapeways.com/forum/t/frosted-ultra-detail-and-spray-paints.80032/