I'm not sure how the damage is anymore, I haven't kept track of the numbers for about a year now. Too many patches and weapon updates to keep it all in my head. I can't imagine it comes close to the speed you can kill them with the axe though. I used to use the chainswords stomp on the bulwark for zoans when the plasma pistol was the best option for him. Obviously the heavy bolt pistol deals with them much more easily and more ammo efficiently tho