In the old days of the Varmint Hunters Assoc, we could join their "1,000 yd club" with a verified kill on a varmint at or past 1,000. I did two, a coyote (1 shot) and p-dog (2 barely missed 3rd center). Today, we practice on a 10" MOA gong @ 1,000 with a 5" painted center, a steel reactive large P-dog, marmot or other varmint gong, or sometimes, we have a wild hair day and shoot at orange clays.
20-24" gongs for 1 mile, but once used a 19x19"