The sheriff had to slap leather when the outlaw reached for his gun.
slap leather
idiomTo make a quick motion to draw one's handgun from its holster, especially in a duel in the Old West.
In the dusty street, the two rivals waited for the signal to slap leather and settle their argument.
As the tension reached its peak, the gunslinger prepared to slap leather, knowing that only one man would walk away from the encounter.