Jason Bourne vs Francisco Scaramanga.

Scaramanga has composite feats from both book and film. His sidearm is from the book, a gold-plated .45-calibre revolver (6 shots).

Bourne has a 9mm sidearm with ten shots.

Fight takes place in an abandoned Western mining town, combatants at opposite ends and cannot initially see one another due to intervening structures. Otherwise, standard arena conditions.

Time of day is high noon. Obviously.