The fact that sniper rifles and carbines are even remotely interchangeable is really weird to me from a fluff standpoint. If we can add the sporting rifle category, surely we can add a carbine category. I'd even like to see some sort of die penalty for using a longarm in tight quarters (like a narrow stairwell) to encourage diversity of weapon choice.
I agree. Although having lots of different ranges might be confusing, the die penalty sounds about right.
I think my houserule for this sort of thing will be an Accuracy hit.
Sniper Rifles use as battle rifles will have their accuracy reduced, since much of the accuracy comes from the bracing, lining up a shot, taking time to aim before firing.
I also like the die penalty for tight quarters. Since size is a big basis, I like the idea of a penalty based directly on it's Concealability modifier, since that is based somewhat on size also. Say, a die penalty in tight quarters = 1/2 concealability modifier....
SMGs, Machine Pistols with extended stocks, at -1
Sword, Sawed off Shotgun, bullpup ARs are -2
Katana, Shotgun, ARs, Sport Rifles and Crossbows -3
Sniper rifles, Bows, Grenade Launchers (as if) are -4
and MGs, Assault Cannons (not actually on this list, but can go here), rocket/missile launchers are -5..
again, using explosives in tight quarters is asking for trouble, but they should still have the modifier, because someone, somewhere, will try..