Using imported objects for Turrets

[Athena]

I'm currently using blender to design a ship. I've imported a turret Base and a turret Barrel object. I can convert the base part to a turret, but how do I connect the barrel part to its "gun state"?

Try going into face mode on the barrel part, copying everything, and then pasting them into the turret while you're in face mode on the gun state.