One little quibble I have with this is that, to my knowledge, gauss rifles do not produce a muzzle flash when they fire. That being said, if this was a modified Gunslinger with autocannons instead of gauss rifles, then it would make perfect sense.
Well, at the time I did the painting, no one had ever built a functioning high-power electromagnetic railgun, so there weren't any photo references kicking around. And besides, if there was no muzzle flash, you wouldn't be able to tell it was firing, so it would be a lousy painting, accurate or not ; )
Since I posted that comment, I saw a couple of videos of modern railgun test firings, and there is indeed a muzzle flash (caused by the projectile moving through the air at such a speed that it literally ignites the air it passes), so you did get the depiction correct. I was wrong. Bonus points for getting it right before the weapons even existed in the real world