For those not familiar with this folding carbine, the bag shown here is 17.5" wide, and that's six 17 round Glock 9mm magazines in there (since replaced with six of the 33 round magazines). The grip has another 17+2 (extension) magazine inserted.
Complete package is 18" wide, 4" thick, and 12" tall, weighs in at 8 pounds, and I have 217 rounds on tap.
Dial in your SUB, you should be getting 2" groups at 50 meters, once you get used to it. Plenty accurate for anything you'd want to really use such a carbine for.
And for others who poo-poo the 9mm, well, out of a 16" barrel you get a good bit of velocity (over 1500 fps with a 115 grain hollow point) and energy gain; you're packing around 600 lb-ft of muzzle energy, making it as powerful of a round as a 357 Magnum from a 4" barrel, something MOST people consider "adequate" for application against 2 legged vermin!
Also have a SUB-16A (a really light, folding rifle that uses AR magazines), and my daily carry is a P-32 because it's so stinking light, tiny, accurate, and amazingly reliable.