So I think this is either a bug or the wording of the unlock is incorrect. I tried multiple times to unlock the perfectly timed attacks perk with 10 consecutive 1 hit kills  using a longlas and normal sniper rifle here is a link showing one of my many attempts using ranged weapons to achieve this perk: https://www.youtube.com/watch?v=7bQPFW72sR4

as you can see from watching that video I should have unlocked the perk from that mission. No matter how many times I did 10 1 hit kills in a row with ranged weapons it would not unlock. However, as soon as I decided to try to get it with a melee weapon it immediately unlocked after the mission.

So either the unlock conditions are bugged or if it's working as intended the Heroic deed to unlock it should actually say: Deliver 10  killing blows with 10 consecutive MELEE attacks. Either way, if it's a bug or wording error I thought I should bring it to the team's attention.