300 PRC or 30 Sherman mag

[Pdvdh]

Reason is going to be tough brass and a case design that is good at disguising pressure signs. Tough quality brass such as Peterson, ADG and some others won't necessarily kill primer pockets running at 70k psi consistently, these companies have tested this, and the 40° shoulder does a good job reducing bolt thrust, therefore not showing ejector marks until higher pressure. So, no pressure signs, and primer pockets hold up just fine, so you run your loads at higher pressure and get more velocity, so that is how you end up with 75-100 fps more velocity with only a small increase in powder.

Cody,
You state the 40-degree shoulder does a good job reducing bolt thrust...

Can you explain that further?

I think reduced bolt thrust mostly is a result of the reduced casing body taper. But if shoulder angle plays a significant role, I'd like to learn more about that.

 

[elkaholic]

Less Body taper reduces bolt thrust and 40 degree shoulder decreases case stretching and also changes burn rate to some degree. it also helps reduce the length of the hottest flame point IMO.
Lower taper helps stretching to some degree too.

 

[Pdvdh]

Less Body taper reduces bolt thrust and 40 degree shoulder decreases case stretching and also changes burn rate to some degree. it also helps reduce the length of the hottest flame point IMO.
Lower taper helps stretching to some degree too.

Thanks Rich,
Appreciate your insights!