The chrome ones have a rep for getting really uncomfortably hot to shoot after a mag on full. Still work, apparently, just really, really hot, as in smoking, much quicker than the plain regular ones. I wouldn't have experience with it, though.
Regarding the absent stock, it makes it a whole lot easier to use the regionally patented, over-the-head-hose'em spray and pray technique. I hope that particular technique maintains it's popularity in that part of the world, at least by the folks shooting at the wrong people over there...