Did the math.
Notes:
-I expect the Reload bulletins affecting Reload duration and not Reload frequency.
-I made the calculations based on the Gren Kar at mid range. Cooldown modifiers are better at longer range than at close range
+3 Accuracy: increases damage by 3%
5% cooldown: increases damage by 1.21%
3% Reload: ... by 0.27%
2% Reload + 2% Cooldown: ... by 0.66%
Basically using all 3 bulletins gives you a 5% increase damage.
There is another factor :
The enemysquad loses 1 member a bit earlier, result of this is a dpsec. decrease of 15%-25% for this squad.