Glock 34 with a forward grip and the cobra stock from FAB. Or even go with a 17L, longer barrel gives a bit more protection for the off hand. The stock folds and so does the grip, making for a smallish package. Not sure if i would want it to be FA, i guess as a lark on the range? If you have a use for such a thing, me I would prefer a big heavy shotgun with 47 extra rounds velcro-ed to it, should I need to defend my house against criminal skeet.