My usual rule of thumb is:
1-harm: melee weapons. They're going to have a lot more trouble getting all their people to bear on targets than people with ranged weapons, so crowbars, hammers, knives, so on come up here.
2-harm: basically pistols, possibly sprinkled with a couple more effective weapons. Revolver and semi-automatic fire.
3-harm: serious guns, as per gunluggers. Shotguns, SMGs, rifles. If the weapon mix makes for a tactical advantage or disadvantage per the fiction, this shows up in the actions taken.
4-harm: big fuck-off guns, as per gunluggers. Usually dominantly assault rifles, there, although MG, sniper, or grenade availability is highly likely.