It's just your normal regeneration. Like whenever you hide somewhere after taking damage so you can wait for your health to come back. That's all it does. Which is pointless if you are still taking fire, cause literally nothing happens. You should get rewarded by the perk for getting a kill. Taking fire or not. At least that is my opinion. If they don't want to change that they can at least change the description to match what it actually does. I'd accept that as a solution as well. :) (Even though that would be kind of lame since the gun has such an awesome name. It sounds like it SHOULD just leech life away from it's victims. lol!)