Sam, I handled one of those CZ's.. It was awesome.. Still kicking myself for not buying it.. If I were looking for a short barreled truck gun that is the one.. Other wise buy any 223 of your choice and have the barrel lopped off.
One of my old pals is pretty sick now.. He most drives around and has a few blinds he watches out of.. But he cut off a heavy barreled .22-250 to 20 inches.. Sounds like a mess, but it was super accurate and easy to get out the window.. He also had a varmint .223 done the same way.. They have killed a pile of game.. I have a couple rifles with fairly heavy barrels cut off to 21".. They are just great for the purpose you describe..
I would also go with the.223.. Ammo is CHEAP!
