Problem is, I can't even make them break at all. Melee weapons have BreakItem="" and RepairItem="" tags in items.xml file, but adding those (or breakitem alone) to a gun makes it ignore it's durability, it can't be unjammed and keeps shooting in jammed state having zero base and critical durability. Entity files in scripts folder don't mention anything about it either.

My guess is those are inherent feats of their parent classes GunDefinition and WeaponDefinition respectively, but I havent yet figured out where those are coded. Maybe someone can point me out there?