Lets see what the damage nerf did.
Quad guns:
First shot, bad shot, 2 missed, 1 crit.
Second shot, perfect salvo, no crits, all deck as far as I can tell. 66.6k damage.
Edit1: second test.
Quad guns, first shot. Bad hit, mostly belt.
2nd shot, good hit, 11/12 shells hit, giving a 61163 damage, if all shells hit, it would have done 66.7k.
3rd shot, good hit, 11/12 shells hit, giving a 57907 damage. damage if entire salvo landed would be 63.7k
Edit 2: third test. Decided to switch to Amagi so I gets less oneshots.
Quad guns, first shot, 11/12 shells landed (calculated with hit %, I fired 2 shots to test range), 59k damage, probably some belt hits
from the location shells, it would have done 64k if all shells hit.
2nd shot, belt hits.
3rd shot, 10/12 shells landed, if all shells hit, it would have done 67k.
4th shot, 11/12 shells hit, if all shells hit, it would have done 57k damage.
Summary: damage nerf had minimal effect. Damage and spread is also inconsistent, leading to these problems. I suggest another damage nerf.