My son & I were duck hunting a few years ago when we had a coyote appear about 50 yds away, broadside to us. He was shooting an 870 Wingmaster, 12ga modified choke and 1 1/8oz of #4 Hevi-Shot. He hit the coyote and it dropped, slowly got up and was hit a 2nd time. The coyote turns away from us and staggers off, makes it about 30 yds and falls dead. We found pellets under the skin on the far side.
I would think B sized Hevi-shot would work farther than 50 yards.
Please let us know how you do.