Strategie

Infantry have rifles, unless you pay for something else, and this is on a squad by squad basis, the game doesn't worry too much about squads with mixed weapons. There is a note that allows 1 NCO to have SMG, but that is it. This isn't a skirmish game with that level of detail. Infantry are just men with rifles, regardless of the models you use. There is no mixed weapon options in the lists.

Of course, you could allow mixed weapons if you want that detail, it is relatively simple to include, just extra bookkeeping (on casualties) and at 15mm (or even 20mm) I don't want to be checking which model is carry which weapon, just counting heads for ROF. Allowing mixed weapons squads seems a fine house rule to me.

Carbines, rifles, meh... all the same at this scale. Hope that helps