John Barsness in his article on the 375 Ruger (see extractbelow, taken from Big Bores forum) says the case capacity is 6% larger than the 375 H&H. That would make the 375 Ruger case a tad larger than mid way between the 375 H&H (and 300 Winchester) and the 375 Wby, 8mm Rem, etc.
The 2.5� Dakota calibres have about the same case capacity as the 300 Wby but the head diameter is based on 404 Jeffery, about .545. The Ruger is about .532, that is, the same diameter as the belt on belted magnums such as 7mm Rem, 300 Win etc.
Personally, I think the 7mm/375 Ruger would be much better if and when Ruger bring out a 300 Ruger as necking from 375 to 7mm is a long way.
by John Barsness
Rifle Magazine, May-June 2007 #231
Case capacity of an unfired case with a 300-grain Hornady round nose seated to the cannelure was 87.6 grains of water, while a new Winchester .375 H&H case with the same bullet seated held 82.7 grains, exactly the 6 percent increase in case capacity that Hornady claims.
