Red Dead Redemption II Legendary Gunslingers Flaco Hernandez
You can find Flaco up to the north-west at Cairn Lake in the snowy area of the map. Once you arrive kill Flaco's men. Once they are all dead walk towards the hut at the back of the camp and call out to Flaco, he will come out and trigger a scene where you need to beat him in quick draw. Once you've defeated him you can take his picture for the record and his special revolver.