One more comment.
I build riflestocks and like to tinker with 7mm's. I have a rifle in 7x61 and the chamber reamer and form and reloading dies for the .275 H&H. With new Norma 7x61 Super cases (available from Huntington) and .275 H&H cases formed from Norma 7mm Remington Mag brass, I find the capacity to be almost the same. Load wise 3000fps can safely be obtained with 160 grain bullets in a 24 inch barrel.