I have 9 ranks of concussions and it shows damage “270% physical damage when lucky hit”. However, this damage cannot crit. I have 100% crit and this damage simply cannot scale with the crit damage. This is clearly a bug. My ugly bastard helm also has a “luck hit: 40% chance to deal 16538 fire damage” and this damage can crit, dealing millions of damage. Concussion can only trigger thousands of normal damage
Do you really mean ‘concussion’ the stun passive? This passive has no damage component 
Why don’t you take a Quick Look?
Each level now grants 30% damage when lucky hit. Decent damage. I did the math. I can scale it up to level 19, which worth 57k damage. It’s almost 5x of ugly helm lucky hit damage
You are right, sorry, I forgot they changed it this season and overlooked it when I checked the passive.
I can confirm that it does not seem to crit, did a quick test with the dummies 
If you compare it to Ugly Bastard Helm, don’t look at the pure damage values, they are not comparable, because other multipliers will be applied to the Concussion damage in the sheet that are not shown on the helmet. But you can compare the %damage.
Ugly Bastard helmet has 2382 base damage, which is about 360% weapon damage. Concussion at level 19 has 570% I think? That would be around 1.6x damage.
[EDIT] Sorry, 2382 was actually the WotB explosion, the lucky hit damage is 9788 or 13163 with GA and 18,225 with perfect stats, so considerably higher 
I see. You are right. Even if concussion is not bugged, it’s still not comparable. It’s funny how the setup is.
Most of my double swing build damage comes from this lucky hit damage. Most lucky hit comes from fist of fate but I also need twin strikes to trigger it as much as possible.
yeah, I think DS has a hard time making best use of lucky hits although the base chance of the skill is pretty solid.
The most successful lucky hit build I know is Chain Lightning with Heir of Perdition, Fists of Fate and Azurewrath as main damage.
I think Azurewrath has around the same damage as Ugly Bastard helmet, but I haven’t found a single one with GA on lucky hit this season ^^.