[Imp]

No need to test really some troops have SMG as an additional weapon so slot 3 or 4 some have as main weapon.
SMG are more effective close up but cannot fire above there max range normally 3.
If they do not have a longer range weapon such as a LMG they are close range fighters only.
Rifle is more flexible not quite as hard hitting close up but can engage at greater range.
Carbines are again short ranged normally 5 hexes but with no close up be benefit.
Other weapons like flame throwers, demo charges shotguns are only effective in the same or adjacent hex.

Riflemen are your all rounders the others are really assault troops pack a bit more punch in close area fighting like woods & towns.
Stats you are intreasted in to understand small arms in WWII
Range max range the weapon can fire, accuracy falls off as range increases.
Accuracy higher more chance to hit, rifle 1 smg 2 or 3
HE kill higher it is the more damage is likely to be caused if you hit.