Just think the half scale gattling gun is simply fantastic - are you working from plans ? your own ? are they available - this is a project I have been wanting to do for some time.
I have gone so far as to 3D print one I found on the web - but it is useless for building a working model.
I presume you are going to use 22 short rimfire rounds.
Do you have a build log on the project on this / other forums ?