.243 is a great coyote killer. I used a 22 250 for my first 25 years chasing old wiley and never had any complaints. Have been using a 223 and 204 for the last 5 years. All four that I have mentioned are great choices but if you don't mind the little extra recoil you will do far less tracking using a 243. Two of the guys I hunt with who are also avid coyote hunters use the 243 with 58gr or 80gr and they both get great results. I wanted to go th the AR platform 5 years back so I went with a 223 and a 204. Both have proved to be good coyote medicine. I like the 243-----22 250------223 and the 204. You can save money and just use the 243 you already have but if you need to burn some cash I would go with a bolt action 22 250 or if I wanted an AR I would go 223.