Number 4 buck is good, if you run across some T size shot it is a little better. You need to pattern your gun, you may find the shorter shells make a better pattern than the 3 inch do. Never know. Larry
I've used both and had better knock down and stay down with the 3" 4 buck. But I think within 30 yards I'd rather be shooting the hornady BB load. Although it's pretty hard to change over after the coyote shows up. 30-50 Yds I'd be wishing I had a load of 4 buck and be ready to offer a follow up shot. On ocasion I'll have the first shot in the chamber a hornady BB load followed by three 4 buck in my super black eagle. Even with the first one a BB load there are times I was sorry I didn't have a 4 buck in the chamber.
I've killed beyond 50yds But now I am committed to always try to shoot with the rifle beyond the 50 yd mark.
Well with all that said it sounds like I'm pretty mixed up and confused. I think anyone who has hunted coyotes and had lots of different situations you realize it's a gamble regardless what decision you make, you just hope it's the right one.
Your answer has been listed, "whatever patterns best in your gun", I personally use Hevi-shot dead coyote loads. These seem to be the best for my scattergun.