We could take weapons off the WMs, but then it's far simpler just to make them useless. I tried a few volumes and the BlockingVolume is the one which really works. Here's what I did:
1. Built a room
2. Put a large blocking volume in the middle
3. Added a light and playerstart
4. Changed the blocking volume's BlockingVolume -> bClassBlocker to True
5. Added xweapons.bioglob, xweapons.rocketproj and onslaught.onsmineprojectile to BlockedClasses
6. Played it and summoned Bio Rifle, RL and Mine Layer (otherwise just add weapon bases)
7. Tried shooting in the volume and from the outside through the volume.
Shooting in the volume instantly destroyed the projectiles without harm, but shooting through it allowed them through (though it could be useful for another type of map :idea: ). Since we can surround the entire map with one of these volumes, it would be impossible for anyone to shoot from the outside in.
Screen:

Anyway, try it, and I hope to see more lightning guns being used in the future!
(even if it's the only weapon allowed)