Originally Posted by
shooting on a shoestring
rbuck351,
Let’s race! Let’s find out.
I looked up the case capacity from wiki for 7.62x25 and see it’s given as 16.8 grains of water.
I just weighed by difference empty and full and found my 30 Super Carry fired brass holds 13.0 grains of water.
So 7.65x25 has 3.8 grains of water more case capacity over 30 SC. Which 3.8/13 times 100 = 29.2% more case capacity than 30 SC.
30 SC has SAAMI pressure limit of 50,000 psi.
7.62x25 has CIP pressure limit of 2500 Bar which is 36,259 psi.
30 SC has 13,741 psi more pressure to work with than 7.62x25.
So 36,259/50,000 times 100 = 72.5%.
7.56x25 has only 72.5% as much pressure to work with.
So it looks to me like 7.65x25 has nearly a 30% advantage in case capacity and 30 Super Carry has nearly a 30% advantage in pressure.
I’m going to guess that’s pretty much a wash. I’ll bet there’s not a discernible difference in real world ballistic performance between the two running flat out. But I’d like to know…