If the only thing affecting how much you do is your light level thing then the very first auto you get would do the same as Suros so no exactly what I said is how it works

If you look at guns in a group like auto rifles then yes they all have the same damage. There are just a few variables that increase the damage. Impact and attack rating. Ever notice how a rare gun with only 246 attack rating but a very high impact can do more damage per shot than a legendary gun with low impact and 300 attack. Its just that the RoF gets higher as the impact goes lower. So the dps is roughly the same. But the vex is a group on its own. Its not really a fusion rifle since fusion rifle bolts dont count precision shots. And its not an auto rifle since it fires fusion rifle bolts. It is really its own class. So imagine the base dps of an imaginary auto rifle is 100. The impact makes it go to 150dps. And the attack rating of 331 makes it go to 300dps. The exact same gun but with an attack of 323 would have maybe 290dps. But the vex already starts at maybe 200dps. Then the impact boosts it to 300dps. And on top of that the attack rating makes it go to 400. Now all those stats are always true. But if your light level is lower then the enemy you are shooting at the damage will be reduced by 30% i think. Im not sure how much it was but it was around that number. So the attack rating of the vex could be 200 for all we care. If they boosted its base damage up it would still end up with the same dps as with 323 attack rating. I could be very wrong but from what i gathered over time this is how it seems to work and its also testable ingame.

My point is.. If you go over the attack rating on the weapon it specifically says" Higher attack power allows your weapon to deal more damage to higher level mobs" or something like that. So a 331 auto will do 100% Damage to a level 31 mob if your level 31. But the vex is not at 331 so it will never be able to 100% damage to anything over level 30. Your light level has something to with it but so does the attack rating. Those 8 points are making it do about 7-11% percent less damage to 32 and 33 mobs and they need to fix that. It may be doing the same damage as a 331 but it's not doing its full damage because it's at 323. They need to fix it.

That logic sounds flawed because how about the weapons with 246 attack rating? Like i said... they are capable of doing more damage when they have a higher impact. This also applies to high level mobs. 331 doesnt have anything to do with level 31. The previous cap of 300 also didnt have anything to do with level 30. Your starter gun has something like 28 attack rating. If you want you can use it through the entire game and it will always do the same damage. Maybe you are confused when you see different damage numbers on very low level mobs. I was doing a level 8 strike and my ice breaker only did like 1300 damage instead of 2500. But the enemies still went down faster than level 26. That is just bungie playing around with the formulas.

Either way it should be at 331