Was a topic of discussion while talking about the N50 competition (where .22lr and air-guns compete on a level playing field).
Some guys wanted to measure proficiency at 100 yards with old school pellets. The dimensions were published and I quick fabbed a target using my laser cad program. I'm not sure the rules were ever ironed out - just made the target to the requested dims.
If you want to try it out, I suggest 5 shots per bull, 5 bulls on a score card for 250 25x max score