That last bit is probably part of it, yes. As far as I know (from reading up on wound ballistics, FBI reports, etc., for purposes of a realistic cyberpunk combat system; I'm no expert or pro, just a nerd), a lot of the effects of being shot are psychological. Some people "shut down" mentally when they get shot.
Conversely, some people are Michael Platt or William Matix, and keep shooting and killing despite numerous gunshot wounds (including lethal wounds), mostly because of their psychology. (Being trained as a Marine or a Ranger no doubt helps.)