I have a RRA AR-15 upper in .223 Wylde with a 20 inch barrel. It shoots the Federal GMM factory load with the 77 grain SMK like a laser out to 700 yards. The muzzle velocity is averaging 2630 FPS. If I am good at getting the wind correct, I can hit clay pigeons at that distance.
I can't stress the point enough that the wind is the only thing that will mess me up at 700 yards on the clay pigeons. Any further than that, the groups will open up considerably. At 1000 yards, I can hit an IPSC size target but really have to get a good estimate on the wind.
I also have a RRA AR-15 upper in .224 V with a 20 inch barrel. It really likes the Federal GMM with the 80.5 grain Berger bullets at 2827 FPS. The performance to 700 yards is not much different compared to the RRA in .223 Wylde.
From 700 to 1000 yards is where the .224 V really out performs the .223. Again the wind is critical with both bullets but I'm hitting the 12" steel plates more consistently with the .224 V than with the .223.
I also have a bolt action rifle with a 26" barrel 1:6.5 twist. Back when the the .224 V first hit the market, I could get factory loaded Hornady with their 88 grain ELD cheaper than Federal GMM in .223! So I still have over 6000 rounds left
That round won't work in the AR-15 as the feed ramp will break off the tips.
In the bolt action, I don't have that problem. It performs better than both AR-15s in either chambering. However, it's a very heavy rifle at 26 pounds!
I plead guilty to being crazy for having that heavy of a rifle but it's really fun to watch the trace of the bullet and see the impact at 1000 yards with little to no recoil.
If you don't expect to shoot anything past 700 yards, I would recommend the .223 with 77 SMK. The factory loads are easier to get as well as reloading components. As far as coyotes are concerned, that bullet might not be a good choice. My only experience with killing coyotes is with another AR-15 and 55 grain Hornady V-max out to 200 yards. It's very lethal but not good for very long distances. It's also accounted for numerous groundhogs with explosive effects.
On the other hand, I think I could easily take a head shot with my RRA using the .223 77 SMK to about 500 yards. That will still put its lights out but won't get much expansion in the heart/lung area.
