For a "truck gun" I wouldn't want a 22. Why a 22? It's not a defence weapon. A 22 is a varment weapon. A better gun for your truck is a shotgun. I have a 12 guage myself, but a 20 guage would work too. Any shell at close range would work. I store mostly 8 shot to shoot doves, etc. but 8 shot at close range would put a hurtin on any person. I have a 22, but it would be more for small game if I needed it.

Charles