I posted this in big game rifle reloading and thought it better here:
From wikipedia
"The case capacity of the .375 Ruger is 99 gr. of water (6.42 cm3) .
The 375 H&H Magnum has a case capacity of 95 gr. of water (6.16 cm3), an increase of 4% for the Ruger
Case Capacity of the 375 Weatherby Case is 105 gr. of water (6.82 cm3) an increase of about 11% over the H&H and 5% over the Ruger. (the FreeBore/Leade for the Weatherby is 0.373 thou. as per the Factory Spec's"
I believe the case capacity of the 40 degree 375 H&H AI is marginally greater (in my rifle) than the 375 Weatherby, by how much I don't know, (300 Weatherby ammo chambers in my AI - I have not fired any Weatherby in my rifle, but have H&H. I don't have any 375 Weatherby ammo or brass.)
I've not found a lot of data on the 375 H&H AI, I have various bullets 200 grain to 300 grain Jacketed and a few cast bullet molds. I am concerned with using Weatherby 375 load data due to Free Bore in the Weatherby.
I'm thinking 3,000 fps with 235 grain to be about top, maybe 2,800 fps with 270 grain, and 2,700 fps with 300 grain. The lighter bullets and the cast bullets will be for practice off-hand shooting.
I plan on working with this rifle this Winter if the weather cooperates.
My 375 H&H AI has a 26" barrel.
