Taking one for the team

I've just equipped this perk for the first time. I leveled it to 3 first. It sounds pretty straight forward.

I shot an enemy in the legs to test it. No buffs active at all, pepper shaker hit for 42 per projectile. Then I let him shoot me after which I shot him again and did 43 per projectile. So it looks like it did something, but unless I have been a lot worse in maths than I thought, thats not 30%.

I am in a team of 3 people, so that can't be the reason.

Am I misunderstanding something?