A tangent but still on subject, the above issue of assembling a drum weapon is one of the reasons I opted for a whisk on C3. Much easier to make and maintain (provided you design it right first time round!)
If you are set on a drum, look at 360's thread to see how Mouldy did the drum assembly on 720 and 722. Its one of the best example out there.
Alternatively you could do what Jamie did for Drumroll, but that had the flaw of welding the teeth on weakened the Hardox.