Case capacity isn't always a good indicator of performance. A lot of the old cases had a high capacity to keep pressures down with fast burning powders (think 375 H&H, 416 Rigby, 404 Jeffrey). With a propellant that is more closely matched to case capacity you can sometimes "do more with less."
The current crop of "Short Magnums" illustrate this point quite well, reduced case capacity does not mean reduced ballistics, at least not with the normal range of projectiles one usually shoots. Once you get to the ultra slow end of the powder spectrum and heavy for caliber bullets, case capacity becomes much more important.
Although unless you have a reason for choosing the 9.5 bore, long range shooting can be done much cheaper with a 338, 300, or 7mm magnum.
Machine guns are awesome until you have to carry one.