This is the 8 Pounder – an 8 shot Gatling, crank mechanism, shotgun with 22 shell magazine. It’s also equipped with a shot dispersal attachment. It’s quite front heavy so a neck sling is necessary to hold the barrels up while cranking.
It was modeled in 3DS Max 2017 and rendered with the ART renderer and physical materials. It was textured with Substance Painter. The exported metal/roughness textures (4k) worked perfectly with the physical material shader.