CIP, the Death of SAAMI and the 7x57 Mauser

Every accident or mishap is usually explained by a convoluted story that is almost totally devoid of logic and common sense. This story is no different. I was reloading some once fired brass that began life as loaded ammunition: Hornady Superformance – Made in USA, Prvi Partizan – Serbian and Sellier&Bellot – Czech. I cleaned them up, ran them through case lube and attempted to size them. Unfortunately, it went something like this…

The Prvi Partizan brass fit the #2 Lee Precision and RCBS #3 shell holders, the shell holders recommended by the respective manufacturers. However, neither S&B or Hornady Superformance fit either shell holder. The shell holder lip spans were measured: 0.410″ for the Lee Precision holder and 0.413″ for the RCBS piece.

The SAAMI cartridge drawing specifies 0.409″ +0.000″/-0.020″ for the diameter of the extractor groove. Checking a random 20% of each brand of brass on hand with a blade micrometer, the groove diameter varied: 0.402″ to 0.404″ Prvi Partizan, 0.418″ – 0.419″ Sellier&Bellot and 0.416″ to 0.417″ Hornady. In checking with Hornady I found that S&B is one of their contract brass suppliers and that the brass is manufactured to CIP rather than SAAMI specification. No big deal. The ammunition is American made, just a component used in the assembly is European.

Where most of the other cartridge dimensional specifications are very close, the CIP specification for the 7×57 Mauser extractor groove diameter is 10.70mm or approximately 0.421″. So brass produced to American SAAMI standards will work with shell holders from reloading equipment manufacturers, components produced to CIP specifications will not. I am not sure why American manufacturers can’t insist on components being made to our national standard as that is what every other country does.

From a loaded ammunition standpoint, these specification differences don’t matter. They only becomes a problem if attempting to reload where it will be necessary to rework an existing shell holder or trial fit until one is found that works. Attempting to make do with one that is too loose may result in a case that has to be forcibly extracted… like the sad story that opened this article. 

Is there an emotional component to this? Sure. It is getting a little old seeing our country being subordinated to accommodate manufacturers’ universal part numbers and lowest bid supply. My guess is we are still a prestigious market and could demand what we want if companies weren’t so eager to embrace the U.N. and become part of Europe. It strikes me that I’m spending my morning grinding down perfectly correct shell holders and pulling stuck brass from dies to make life easy for some machine apprentice set up guy in Czechoslovakia.