Very easily. If I remember, the officers were scrambling for cover when Matthews (a former Freeper, btw - friend of yours?) let loose with his gun. Normally, a buttock shot hitting vital organs would be kinda weird, but the gun Matthews used was (again, if I remember) a Makarov. Sporting a cartridge that is something of a performer, and which can - with the right bullet - punch through body armor. Which is probably why he selected this not really common pistol.
It appears to be you who are deficient in your firearms knowledge.
A Makarov fires a 9mm short that is somewhere between a .380 and 9mm Parabellum/Luger in power, probalby closer to the .380. Maybe you mean a Tokarev, which fires the 7.62x25 round, which is a pretty hot round, if somewhat lacking in the diameter department (7.62mm is .30 caliber).