This WWII-era German MP40 SMG is rigged and ready to go, I used this myself when experimenting in Unreal Engine 4 and 5. Textures are 4096x4096. FBX/Maya formats include bones for magazine as well as the rounds inside, in order to animate reloads, as well as bones for trigger, mag release, ejector cover and charging handle. There are also bones positioned/oriented appropriately so you can spawn muzzle flash and eject casings. Main geo is skinned to a bone near the top if the hierarchy, with a root bone at the top skinned to nothing so it can be plugged into a character socket.