I am not sure how practical it is, but this has a certain coolness about it.
http://www.youtube.com/watch?v=TmP7h2znk1Q
http://www.youtube.com/watch?v=TmP7h2znk1Q
That's almost as cool as the triple barreled revolver.
http://i.kinja-img.com/gawker-media/image/upload/s--maT-fosq--/17m08391rchjzjpg.jpg
I can see the reason for being able to fire three .25 ACP rounds at once, given the very low power of the round. A .22 Rimfire Long Rifle has more power than the .25 ACP. Multiple hits would make up, to an extent, for lack of stopping power. However, if I were given the choice of that or a nine-shot .22 revolver, the .22 wins hands down.
I guess if I want a high-capacity handgun, I would prefer a semi-automatic over a revolver. For a hunting handgun, a long-barrel revolver would be preferred, with a detachable shoulder stock, and 5 or 6 round cylinder.
I keep thinking that an interesting handgun/carbine would be a Mauser in say .30 Carbine caliber with a 12 inch barrel, collapsable shoulder stock and 15 and 30 round magazines.
With .30 carbine in that length barrel the muzzle flash would be blinding and the round would have less power due to not all the powder burning before the projectile exits the muzzle.