I used to be extremely aggravated, but now I'm just amused.
In these discussions about the practical range of .223/5.56, there's a huge amount of what amounts to urban myth.
FACT: The practical range of the caliber is limited to the point where the bullet retains enough velocity to appreciably fragment within the target, thus transferring energy to the beast that you're trying to terminate.
This is exactly why I, and anyone who has the remote inkling of a clue about how these things work insist that this cartridge is limited to 250~300 yards.
Try this utterly simple test:
Pick a medium; any medium, like cantaloupes, defrosted turkeys, or whatever you prefer along those lines. Something that has enough wet mass to cause a bullet to upset upon impact, and large enough to indicate the extent of destructive force.
Set one out there at 200 yards. Another at 300, and another at 400.
Use whatever load you've settled on to be your sure-fire fight stopper, and use that same load on all of the targets.
The 200 yard target will be relatively easy to hit, and the devastation will be pretty much as you expected.
The 300 yard target will be notably more difficult to hit, and the degree of destruction will be immediately apparent to be less than it was at 200. In fact, no matter what projectile you choose, something like a melon will NOT "explode" upon impact, like they do at 200.
The 400 yard target will be MUCH more difficult to hit, and will most likely show very little, if any upset. This is because the bullet has slowed to the point where it does not deform.
When you finally do make a decent hit on your 400 yard target, break out your trusty .22LR rifle, and shoot that target again, at close range. The relative damage will be very similar between the .223/5.56 and the .22LR, unless you were using a hollow point with the lowly .22LR. In that case, the little .22 is very likely to do more damage.
This demonstrates that 400 yards is beyond the "effective" range of the .223/5.56. You can still poke holes at 400 yards and beyond, but to very little effect, because the bullet can't possibly deform and transfer energy.
If you are facing a charging hoard of drugged maniacs who are determined to annihilate you and all you stand for, it's a good idea to poke holes in as many of them as possible, from as far away as possible, and hope that it makes a difference. If you're trying to make a humane kill on a game animal, or place a shot that will make that bad guy quit trying to kill you, 300 yards is the working limit.
The M4 is a lot closer to being a 500 yd gun than the 12 ga is to being 200-yd capable. Same with people who "think' that the 30 Carbine is a 300m rifle. The 30c is a joke at 200 yds, actually. check out the wind drift charts for it.
