Not Fun
Would be a fun SBR project . . .
Actually, "fun" would not be my first choice for an adjective.
There have been a number of .30 Carbine pistols. Immediately to mind are the Enforcer mentioned above, the 1944 S&W (hand ejector) revolver, The AMT Automag III, the Thompson Contender, and the Ruger Blackhawk in .30 Carbine.
One of the most common commentaries on .30 Carbine fired from a pistol is the astonishingly loud muzzle blast and daylight-visible fireball, the result of a substantial amount of powder still burning as the bullet exits the barrel.
I'm a big fan of the M1 Carbine, but after doing a little research on pistols chambered in what was "obviously a pistol cartridge," I decided to make my "companion" rifle/pistol set a .38/.357 carbine & revolver instead.
You
could custom load the .30 Carbine with a different powder more suitable for pistol use, but then that would probably require modifications to the carbine to handle it properly, and you'd pretty much be on your own for ammo after that.
Probably the worst pistol report scenario I can imagine is a home defense action involving something like the Enforcer or the Blackhawk in an enclosed space without hearing protection. Something like that could cost you some or all of your hearing.
And that, I believe, disqualifies it for use of the word "fun."
Your mileage, of course, may vary.