Question about "Increased Action Damage"

[Cascadi]

Hi I got a Question for everyone here ... is it just me or does the Machinist Trait "Increased Action Damage" ... do pretty much nothing?
The Tooltip is "Increases base action damage and autoturret damage by 20%." for the Lvl 2, the German Tooltip is even more exact in that it specifies that all Damage from Commandos besides Autoattack is increased by 20%
To check at Lvl 50 I used Split Shot (Potency 140) on the Dummy and then compared it to Hard Shot (potency 150) from the Bard.
Gear was the same kind (Improved Ironworks for weapon).
Split Shot did Between 350-370 Damage
Hard Shot did 370-400+
I ignored criticals for this comparison.
If Split Shots Damage is increased by 20% it normally should do more damage than Hard Shot or am I wrong.
By the Way I checked and Machinist and Bard had the Same Dex at that Level for me so that's not the Reason.

Archer also has the trait Increased Action Damage so the difference you were noticing was the potency.