Scripting a rotating weapon on the spot

Hello, ive made a very small map (Halo 5) just for warming up and messing about on and want to have a power weapon high up rotating on the spot, kind of like they do on weapon pads cos using a weapon pad would look silly with having it spawn so high from the ground (requires a man cannon to reach)

but,i cannt figure out the scripting and require help

 

figured it out, but it looks jagged and a bit un natural but oh well, lol

 

yeah its a bit of a shame, but nevermind, i got it looking the best i could