Belted magnum nickel-plated brass

[reynolds357]

The rifle is also chambered with a match chamber.

A match chamber is a common factor that equally effects both types. I am not really sure what a "match chamber" is. Cut to minimum SAAMI spec? Polished?

 

[stagpanther]

Cut to minimum SAAMI spec?

I believe it shaves a couple of thousandths from the delta between cartridge and chamber specs. I had some issues with initial sizing of cases to get them to chamber easily but my impression is that the parent 375 H&H was originally designed to fit "loosey goosey" chambers for increased reliability and that might be why I had to size them down a couple of times to get a good fit.

 

[reynolds357]

I believe it shaves a couple of thousandths from the delta between cartridge and chamber specs. I had some issues with initial sizing of cases to get them to chamber easily but my impression is that the parent 375 H&H was originally designed to fit "loosey goosey" chambers for increased reliability and that might be why I had to size them down a couple of times to get a good fit.

The 7 STW is a blown out h&h case anyway. They got rid of almost all the taper.