using 110-grain Hornady bullets over 19.0 W296. He was zeroed 2.5" high at 100, and that put them dead-on at 200. So for various purposes should need no compensation out to, I'd guess 250. Probably have dropped a fair bit at 300.
I was trying some black powder loads in .45-70, but light was such I had problems at 200. I'd really like to figure a way to mount a scope on the thing for load testing without drilling and tapping holes.