That's fine, but I still like to shoot way farther than that and need a heavier bullet.
I understand you want to shoot farther and need heavy bulletts. If 224 caliber is your choice I would ask if it's target range of field shooting? Also what is you're definition of accuracy?
I've carried the 5.56 in the M platform in the field for a few years, for over 30 years I've loaded for the AR 15 A2 20" barrel with a 1 in 7 twist. I've shot range and field with the rifle with 55, 62, 68 grain and heavier projectiles.
I have found that any projectile over 68 grains in this platform with 5.56 NATO cartridge reduced velocity too much creating too severe a ballistic curve and too long a flight time for any work other than range work.
If your criteria for field accuracy is a 3" to 6" circle, time constraints, target ranging and other variables in the field are much more easily overcome with a 224 caliber bullett pushed much faster than a 5.56 case capacity can handle.
In my experience with iron sites in random conditions with sufficient target acquisition time, man sized targets are easily and regularly hit out to 400 yards with 55 and 62 grain projectiles. My rifle with quality 68 grain bulletts stretches that to 500 yards.
When I scoped the rifle with heavy bullettes and reduce that target size to 3" to 6" (varmint size) the results for me were at 3" (hit every time, most wind conditions) no more than 300 yards. At 400 yards the hit percentage dropped to as low as 40% in high winds.
The next problem was that if I moved to a 6" target the hit percentage at 500 yards was about the same, 40% in wind.
I came to the varmint part of this 224 caliber backwards, starting with the 6mm Remington. I had good success with it and tried the 223 and 5.56 in both bolt and AR platforms, then I ran into the limits of the case capacity.