i purchased a gun model from the market and when i opened the skeletal mesh of it the clip bone and barrel bone are greyed out and also my mesh is missing a barrel, a clip, a stock and a sight and those item came separately as static meshes and i really need the full build of the gun model, i tried to create a socket to the bones but it just a preview only and nothing seems to work what should i do?, how can i add this meshes to the skeletal mesh and create a full gun?