Ever since I published the Shootist’s Challenge, https://thetacticalprofessor.net/2024/10/25/shootists-challenge-target/, the question has arisen, “How far is ’10 paces’?” There is finally a definitive answer.
Although Wild Bill Hickok didn’t have access to the CIA World Factbook definitions of Weights and Measures Appendix G :: Weights and Measures, I think that tome has supplied the answer.
paces (US) – inches 30
Wikipedia provides us with a prose rendering and background of this measurement. “In the United States the pace is an uncommon customary unit of length denoting a brisk single step and equal to 2 1/2 feet or 30.0 inches.” It also provides the link to the CIA World Factbook for which I am grateful.
I accept that definition, which would make the distance for the Shootist’s Challenge 25 feet. The updated target is attached.
My thanks to Mr. David Fortini whose question led me to the final answer. He receives whichever of my books he would like with my compliments.
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tacticalprofessor 
My interpretation is:
The one time I fire, it will be a Contact Wound, from which there is no possibility of survival. It harms the ecology to waste ammunition. I will “Duel” with anyone who protests.
?! … well, ok then.