IMHO, ahem, stay away from the Kel-tec that was suggested. I've seen one of them break their stock off in carbine class. Read other reports of the the same. Second, the lever gun. Better learn to run it reliably. Just don't buy it and toss it in the truck for the zombie hordes. Saw a guy at a carbine match, screw up being Lucas McCain with short strokes. Then it jammed and we had to wait while he and the SO figured it out.
Lots of folks around here have the Ruger 9mm carbines with the plain barrel. Yeah, 9mm, stopping power - OMG!