Gunfight in episode “Unforgiven”

During the showdown between Paladin and gunfighter Ronson (Hank Patterson) they start talking about the range of their weapons. Paladin rents a rifle with the longest barrel from the gunsmith which I assume was for accuracy. During the gunfight it is mentioned that Paladin can fire at a longer range than Ronson but they really don’t seem that far apart. Ronson tries to close the gap as much as possible before Paladin fires at him (with fair warning) and when he fires he hits Paladin in the hands. It looks like he was firing birdshot at Paladin based on the wounds on his hands. This seems odd to me because I wouldn’t expect a professional gunfighter to use birdshot so I am a bit confused.