How would I make a model rotate while anchored?

This might not be much of a scripting question but maybe somewhere in this ill need a script. Im making this laser model which I finished the building but I need to add some effects so its more atmospheric. The part model trying to make rotate is the model in the middle called Barrel. I have one idea of doing this but I dont know how to plan it out. I could weld the barrel model but I wouldn't know how to make it rotate. The laser model is 200+ parts and can be found here: https://www.roblox.com/library/748473035/Laser

I forgot to say that I tried the torque attachment and it didn't work while anchored and I dont know how else to make it spin.