I should have realised about the additive damage, feel a bit dumb now.

i swapped out serration for galvanized chamber and it seemed to work so thank you very much :D. I was getting worried because i seemed to have hit the jackpot with this riven. Do you think hammer shot would be better than hunter munitions also?

Its the braton prime, 4/5 dispo. tested on corrupted heavies lvl 135. I'm also using arcane merciless but tried to stay away from multishot due to the ammo consumption in incarnon form.