M10 Mag well question

[Ovidius]

Was this protruding tab also a feature of M10s chambered for 9mm Parabellum or was it exclusive to 45 ACP?

[flyer7412]

Those are only found on the .45 ACP guns. Because the original Powder Springs M10’s in .45 used slightly modified grease gun mags, they needed to add those recesses so the grip could be the correct length while still allowing the magazine stops to be in the correct position.

[Fulautotank]

These can be found on 9mm Mac10 that use sten mags.

[Ovidius]

Thanks. I couldn't quite understand the reason for those bulges, one on each side of the mag well. I thought they were put there purely for aesthetic reasons. But looking at the original grease gun magazine it has a magazine stop somewhere in that area so I suppose then that the bulge allows the grease gun mag to slide in further into the mag well allowing the mag well to be made longer.