Simple methods to unlock "Swift Justice" achievement? (Get a kill under 0.6s in Duel)

[Frank Castle]

[Bite]

On the first duel against Pat Garret, pull your gun right after the third Heartbeat, that's the exact moment when he'll draw so your reaction time should be alot faster than usual and you'll get an honorable kill too.

It goes without saying to obviously keep your Focus and Speed as close to 100% as possible.

[nereksnadu the Rakusan]

it seems to be random, i had alot of 0.61 - 0.7 shots and then suddenly i had a 0.45. this was over maybe 20 tries in duel challenge and general campaign, and i don't believe i suddenly made such a change in reaction time so i think it was random that it was suddenly so quick.