(adsbygoogle = window.adsbygoogle || []).push({}); without using a sniper rifle. I just did it on crash with the scar and cold blooded. I thought it had to be a sniper rifle bullet but that is collateral damage. I was amazed because a lot of points popped up on my screen and then it said all pro and double kill.

i've had 2 all pro's, one with barratt the other with intervention, and both times i got the collateral damage challenge

All Pro - You have to get a double kill but only ONE of the kills has to be an HEADSHOT

I got it in a Hardcore TD the first time in the highrise spawn. I wet myself and the funny thing is that it only showed one guy killed with a headshot and the other one wasn't a headshot

like i just said, only one of the kills has to be an headshot

Explains a lot since the second time I got it I did the same thing however the third time was 2 headshots legit =D

completed all challenges except guns

ive got it easily i mean theres always 2 enemies around well most of the time near eachother

Seriously? then when i did that collateral i was too low level to have all pro challenge unlocked because i did a hs

Model 1887s akimbo hardcore S&. It was pretty sick since I only shot once.