I think bolter is still fine because of the rating impact it gives. A powerful weapon is okay as long as the ratings go up accordingly. The 20 pct crit and rapid fire match the TT impact where it does 2 wounds and has rapid fire.
Its one of the best ranged weapons, definitely not the best weapon. Not sure what that would be but I know if you run a gang with all bolters you’ll get killed against a gang with a balanced mixed of power weapons. One on one for gangers with maxed skills, I’d prefer to take a power weapon vs a bolter.
Plasma gun has a higher strength, crit and defense modifier in this game. I forgot if it’s missing rapid fire but it should also have it per TT. I know it’s missing the higher strength option where it has a chance to explode.
Looking at TT, the bolter is actually better than a heavy stubber except for the range. Heavy stubber has same strength, just more range and double rapid fire and only does one wound instead of 2 like the bolter. I.e the mobile bolter seems to match the heavy stubber comparison in TT.