Being a game, one of the more "annoying" issues is the limited ability to accurately reflect the effects of the various calibres, etc. Basically we're stuck with 1, 2, 3, or 4 D6 for most of the more common weapons with no provision for handloads, varying projectile weights, etc.
Of course it
is a game so suspension of disbelief is a given.
Any variation in weapon firing, etc that's not already covered by the basics (recoil, rate of fire, base damage, etc) is fairly easily covered by a little roleplaying. If a weapon is described as having a large muzzle flash (AK-74U as an example) then there's certainly nothing wrong in playing it that way.