Fire the gun where it glitches with the constantly charging beams of light. Save, reload. Pull the trigger again and it should fire the beam of light, be careful not to be too close where you are aiming. This fixed the problem for me.
Jed, I'm having the same problem. I fired it once on a Deathclaw. 24 hours later I tried shooting a Super Mutant and it didn't work. Three red beams just disappear and reappear randomly. When I fast traveled it went away. I haven't tried the gun again.
I actually got this bug too, really weird. And when I loaded my autosave my right stick wouldn't work. All my other saves were fine, so I just loaded them. Don't know what causes it.
got same problem real annoying since i went out of my way and ruined my rep with ncr to route power to ARCHIMEDES. n this needs to be fixed. i have tried even weapons repairing the darn thing nothing.