I have been experimenting with coyote loads for 3 years with both my 243s and this is what I have came up with.

3 years ago I was loading Hornady 75gr V-Maxs at max load and the 75gr HPs, blew thru everytime I shot a 'yote.

2 years ago I was shooting Sierra 70gr Blitz Kings, I had about a 50 percent exit wound.

This year I switched back to the 75gr Hornady HPs (they redesigned them with a bigger HP cavity) loaded them around 3200fps (advertised I have no chrony) and I have shot 17 coyotes with them this year, not a single exit hole yet.

I decided to test them on smaller critters to see what happens. The smaller critters were in the form of jackrabbits. They all exited, no matter where I shot them, anywhere from a nickle size to baseball size hole, depending if I hit bones or not.

As long as you load the 243 down a ways exit holes will not be an issue on 'yotes, fox I am not so sure about. I have my gun sighted 1.5" high at 100 yards and I can hold dead on the back of a yote at 300 yards and drop 'em in their tracks.

What do you need a muzzlebreak for? The 243 doesn't kick!?!?! You would be better off buying that pachmeyer (sp) slip over the shoulder pad in my opinion if recoil is that big of an issue.