no but you cant use buckshot. #4 buck is as big as you are allowed and is a little overkill for fox unless you may have a crack at a yote also.
number 4 is still buck shot and thats what i use.. what would be better for them them then always used it dont make as many holes when you shoot... and what do you use to sew then up? before or after fleshing?
i might sew up a big hole from a slice with a fleshing knife or something but reds dont need fleshing if skinned right most time. i've never heard of someone sewing up pellet holes from a shot gun.
if you feel like sewing have at it. shoe factory thread or dental floss works good whatever needle makes it easy for you but i wouldnt waste my time with pellet holes.
I like 3" 4 buck or #2 lead shot. And no, you don't need to sew up the buckshot holes. I hit one at 8 - 10 steps one night with 4 buck, I think he took all 41 pellets, and once the hide was turned fur out, you couldn't even tell. #4 lead would be fine for fox though, I'm sure. Always liked my #2's myself, though.