I have shot several .30 Carbine pistols, mostly the Automag III, I believe. It as not the same pistol as the other Automags, more like the .22 Mag. they made.
The ones I shot were pleasant shooting with very mild recoil, though considerable flash. And they never offered any advantage over a good .357 Magnum revolver.
Though I have seen some of the old Kimball pistols, I never had the pleasure of firing one.