Artillery. Before 1900 pretty much anything that served in the artillery. I will be disposed towards being inclusive here. After 1900 something built for artillery, not for AT or Flak roles. Self-propelled or towed is fine. Self-propelled guns (StuGs, SUs), tank destroyers, tanks, are out. Mortars are fine. If it’s a man portable mortar, needs to have a figure or so with it.