So I grabbed the Boltor incarnon this week, and while my initial impressions have been great for the most part, I noticed a few things that at least seem to be broken with Crimson Overture specifically (one of the 2nd Evo choices).
Unlike most (maybe all?) stacking buffs, the duration of each stack is tracked individually instead of resetting with subsequent kills, resulting in you being able to lose part of the buff despite very recently getting another kill. For example; if I kill 2 enemies at the same time and a 3rd enemy 4 seconds later, then I will drop from 3 stacks down to 1 a second after that 3rd kill, with the remaining stack decaying after an extra 4 seconds as expected. Compare this to something like Primary Merciless, where the stacks fall off one at a time and the duration resets with every kill or decayed stack, and it just seems odd if intentional to the point where it feels like a bug
The incarnon mode itself only benefits from the additional damage with each stack of CO, and seemingly does not take the ammo efficiency buff into account. I tried comparing the rough amount of time I can hold the trigger with and without the buff several times and it seems consistently identical, when the buffed version should be able to fire significantly longer with the 60% chance to not consume a shot. Attached are 2 comparison clips where I built purely fire rate (38.53 on the incarnon, if the exact number helps) and used up a full charge. In the first I simply fire at a wall without any stacks, in the 2nd I fire through a group of level 1 enemies to keep the stacks up - in both cases i can only fire for about 5 seconds before running out of ammo.
Everything else on the Incarnon Boltor seems to be working fine (although the numbers on the 3rd Evos seem odd with one being objectively better than the other two choices), so it should just be CO that needs to be cleaned up. Clip 1 - Example without CO Clip 2 - Example with CO stacked