Personally I think too many hunters have just written off the 223 for coyotes. I shot a 204 for several years as well as a 17 Rem. and both worked well enough but I was mostly shooting over a bait pile where shots were easier to select. Then I spent some time (mostly calling) with the 6x45 shooting 55 gr. ballistic tips and it did quite well in fact so well that I named it the Parvo. I spent a couple years shooting this combination unsuppressed and finally suppressed.
Somewhere in there, it seemed the coyotes were not coming in as close and so I switched to a Ruger Predator in 243 shooting 58 V-max. I made shots out close to 400 yds., but the 22" barrel with a 9" suppressor added made the rig a bit ungainly especially getting in and out of the truck. I killed 85 coyotes with that combination in 2020.
Last fall, I decided to switch to my 16" barreled AR in 223 shooting a 50 gr. V-Max partially because the rig felt so much handier with the 9" suppressor and more compact. I was pleasantly surprised at how well it did. I killed 46 coyotes with it during the winter/spring this year. Most were one shot kills. Now I didn't take any 300-400 yard shots. In fact about 250 yds. was my longest shot, but I found that since I knew I didn't have the punch and reach of the 243, I was more patient and able to call the coyotes in much closer without getting impatient and firing away.
Finally, while I've done it myself, a 400 yd. shot with thermal is a long punch under the best of conditions while calling.
