I'm involved (vaguely) in the TinyMUX programming community (an old text-based game server/engine). I'll tell you right away that finding the "perfect" random number generator is a Holy Grail of sorts. One can "seed" the generator from the timer (a rather common manner), or from a number of other things. The more things you use, the more random it gets (sort of), but it also takes more time. This increased time CAN improve randomness! I remember some old programming experiments where I could usually deduce the die rolls before they showed up... simply because the bloody computer was so old that I could guess about where in the timer it kept landing (basically it was picking a predictable series of numbers based on the regularity of the processing). The same program on a terribly faster computer would spit out all 30 random numbers the same or very close together... because it apparently was using the same time or clsoe times for many of them.
So basically yeah, the random numbers may be a bit less random than you think (though probably more than you think now

). On the other hand, don't forget things like Warhead Value (or am I thinking splash damage?). Grenades almost always seem to kill at least one man, regardless of the hit %. Throw multiple units in the hex and you've got a bloodbath (which is why I always try to herd Bad Guys into one hex

).