I bought the gauge below for .308/7.62 for checking the sized machine gun brass case and as a final "plop test" of the loaded rounds.
The gauge is cut with a match finish reamer and all my cases sized with the small base die fit perfectly.
After the first firing and forming to my chamber I will use the standard .308 die.

JP Enterprise Semi-Auto Case Gauge .308
Optimized for semi-automatic rifles, the second generations JP Case Gauge guaranties function of your ammo. If it fits our gauge, it will fit even a minimum-depth SAAMI chamber without interference.nterprise



Below the Wilson and Dillon .223/5.56 case gauges only check shoulder location. The JP Enterprise gauge also checks case diameter and as you can see the base of the case does not drop as far into the gauge. I had a few once fired Lake City 5.56 cases sized with a standard .223 die that would not fit this gauge and was loading for two AR15s and a Savage .223. This is the main reason I asked the question which die everyone was using with 7.62 machine gun brass.



I use the Hornady cartridge case headspace gauge for checking shoulder location, but the JP Enterprise gauge was the only gauge I could find that also checked case body diameter.

And since I was getting different diameter readings using the standard .308 die I decided to size the cases once with a small base die.

And again thank you all for your help and advice, after over 47 years of reloading this was my first experience using machine gun brass.