So Countdown's ability states:
When defending, if you are not stressed during the "Compare Results" step, you may suffer 1 damage to cancel all dice results, if you do, receive 1 stress token.
And Gunner states:
After you perform an attack that does not hit, you may immediately perform a primary weapon attack. You cannot perform another attack this round.
So, if Countdown uses his ability and cancels all results, he is technically not "hit". No damage from dice is actually landed during the attack, instead Countdown cancels the dice and takes a damage card and a stress. So Gunner could process and the attack could make another attack against Countdown, and since Countdown is now stressed from using his ability he wouldn't be able to use his ability on the Gunner attack.
So then is Gunner just a super hard counter to Countdown's ability? Does anyone disagree that this is how it would work? Seems like a weird interaction to me.