Hope this isn't the wrong approach, I shot a Mach4 for a couple years with Todd Kindlers 30's. I still love that setup. I killed a ton of coyotes and was really surprised it became my go to rifle. I stepped up the velocity and went to a 223 based 17. Similar results with heavy bullets. Try heavies, BC goes up penetration goes up wind drift goes down. We aren't talking huge bc's, but Berger still makes a great bullet for the 20's. If you aren't saving hides shoot them with a 50 Caliber. If you are looking for a stellar hunt. Shoot them with a heavy 20. I have no experience with 20's other than light 20's out of the 204 Ruger. Relatives that shoot them and ask me if I want them. I always do because they are worth dealing with here in Western Wyoming. Lot's of sewing. The 221 Fireball is a perfect platform for a 40 lb. critter. wether it's 30 caliber, 22 20 or 17. Great little cartridge. Hope this was worth your time.