The .375-.416 Remington is like you suggested; a blown out .375 H&H. It holds significantly more powder. It is about the same as a .375 Weatherby. Not as much as a .375 A.I. which is what I asked for. I think that is shortened to "improved". I didn't do anymore business with that 'smith. By the way it is the same case as the 7 STW or the .358 Alaskan.
I can fireform new brass by firing factory load.375's. I loose about 100 feet per second. I prefer to purchase new brass to load.
