The rules on the UWL website are highly outdated. The PBN section of the forum has some updates, although not compiled.
Essentially, any marker which can be capped at 12bps can use whatever hopper they like. Markers which cannot be capped (mechanical, or inadequate board settings) must use an approved hopper.
The Heavy Gunner, of course, can use whatever.
Originally Posted by HP_Lovecraft
There is no way you could safely control 4 seperate guns remotely. Some players (ie Lasoya) can not control a single gun, while holding it, safely.