If you are just wanting to do it to do it, I'd say have at it, and enjoy yourself.
As far as being practical, that's why they make submachine guns. They're more accurate than pistols, have a higher rate of fire, and are useful in limited situations.
A 9mm pistol cartridge in a carbine or rifle length barrel will still be a 9mm, with a few more FPS.
When I was in high school, a friend a had a Ruger .44 caliber Deerfield carbine, not exactly but pretty much a 10/22 chambered for the .44 magnum pistol cartridge. It was a really cool gun, but it was too much for small game and not enough for big game. It would make a great camp gun or survival gun, but if you're going to carry a rifle to hunt big game, why not carry a regular rifle and not have to worry about shooting an underpowered cartridge (for big game)? It was an awesome gun, but it it just didn't make sense. (BTW, I'd love to have one, even though I'd have no practical use for it...)
That aside, I think it's a cool idea if you're just looking do it for the sake of doing something different.