User blog comment:Gundam Legilis/Volume 1 Weapons In Depth- StormFlower/@comment-2006510-20140621104703

I believe it was intentional that the bullets don't do much damage.

I mean think about it: Ren uses his weapon far more for unusual uses, such as his landing stragety and stabs, rather than primarily relying on the bullets. And when he does fire, it's never to do damage, but more to keep them occupied/distracted. In other words, probing for weaknesses, openings he can exploit - and once he finds them, either stab it, or fire directly at it to cut it off (as he did with the Deathstalker's tail, though he got thrown off midway through), or other such things.

Far more of a stragetic go-for-weak-point use, rather than simply for power imo.

Though I admit, this is based off what little we saw in Vol. 1; could be more to confirm/deny this