Here is my Polish PPs-43c, this one is in the 7.62x25 caliber. It's about as simple as you can get for a firearm, after shooting it, you flip the top cover, pull the bolt and spray it out, dry it off with compressed air and re oil. Because of the "locked" folding stock it's kind of uncomfortable to shot as a pistol, but it is deemed by the ATF as a pistol. From the hip, it's a blast, you can also do the old Uzi hold and shoot it. IF you cut the stock loose, you will have created a short barreled rifle, which if you don't have a ATF tax stamp, can get you a vacation at Club Fed.
All loaded up on it's first outting, the mags hold 35rds of 7.62 Tokarev, and if you reload, I wish you luck, it will chuck empties 20+feet. After a few jam ups at first, it's worked without issues since.