My 2 cents on the gun skills thing.. and not to make it sound like insulting anybodys intelligence, just kinda listing my experience (its fun having gun freaks for friends.. especially when you get to shoot a perfect condition pre-ban tommy gun, and a 50 cal rifle.. the bruise isnt much fun though..)
I cant really see SMG being stuck in with Rifles, they are more compact, generally use lighter rounds and useable one handed, and general shooting style is "spray and pray" because the shorter barrels dont generally give a good aiming accuracy..
Even an Assault rifle is good bit diffrent then your average rifle. They tend to be automatic leaning towards spraying bullets while aiming some, but even then your not aiming as carefully
Rifles are made for aiming, usually bolt action, pump, lever, ect, some semi auto but that tends to take away from the accuracy factor. They use big bullets that spin nice and clean for a good accurate shot that can do some good damage even to armored targets generally by putting the holes in the place where armor isnt to thick.
and a Shotgun.. same shape and all as a rifle generally, but fires nothing like a rifle, even if you use slugs.. Pellet and buck shots best used for light armored targets at close range in causing a good heavy spread of damage over the body, and a Slug... well.. then your just trying to make a REALLY big hole in them, and the heavier the slug the harder it hits, the gun against your shoulder and against them..
One nasty thing in one game i saw and wasnt sure if it would work was a Copper slug, not a solid one, was mainly done like a shaped charge, didnt have the explosives but the force of the shot and impact on target alone was nough to splatter most things pretty well and peirce armor.. Anybody know if that would work well, or would copper be to hard or to soft for the gun to shoot properly?