This is a master gauge used to test machining tolerances on parts of an M2A1 machine gun barrel. Not quite in my specialty as a machinist. This is not going to be an item easily found on the interweb. This was likely produce in very small numbers as any facility machining M2A1 barrels would only need one master gauge. To get a more detailed identification on this you will have to seek men knowledgeable about history and machining after all it is likely 70 + years old. Could have quite a value to certain collectors.

This is a master gauge used to test machining tolerances on parts of an M2A1 machine gun barrel. Not quite in my specialty as a machinist. This is not going to be an item easily found on the interweb. This was likely produce in very small numbers as any facility machining M2A1 barrels would only need one master gauge. To get a more detailed identification on this you will have to seek men knowledgeable about history and machining after all it is likely 70 + years old. Could have quite a value to certain collectors.

References:

https://www.logsa.army.mil/psmag/archives/PS2016/769/769-42.pdf