So I love shooting rifles since I've always been far more accurate with them and enjoy firing them more as well. I debated a larger caliber like the 223 or 308 but that meant going with a AR or AK style weapon which I've never been a big fan of their designs. So I decided to go with a 9mm since they cost a quarter of the cost of a AR-15 and the ammo is significantly cheaper (well when we're not in the middle of an ammo shortage it is...). The non-AR 9mm carbine market isn't all that large but I decided on the Kel-Tec SUB-2000 which actually uses Glock magazines so I can share between the carbine and the pistol and I only have to stock one type of ammo as well which is hard enough to do right now. It also folds in half allowing it to store in a compact 16" area which is the length of the barrel. Also thanks to the military spec Glock 18 there are official 33 round 9mm magazines I can use which helps put it on par with the AR/AK weapons. It doesn't have the range or penetration of a 223 round, but in my opinion that's what a nice full sized rifle is for.