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Posted On: 11/30/2022
By: Eddy
A: Thanks for reaching out Eddy! The 5.56 and 223 possess virtually identical exterior dimensions. If you put the two side by side, you could only tell the two rounds apart by looking at their headstamps. But they are not *truly* identical. The 5.56 is loaded to a slightly higher chamber pressure. The 5.56 chamber's leade is 1/8" longer than the 223 chamber's leade, which provides the extra space its slightly more potent propellant charge requires for safe combustion. I'm getting technical, but it's important to appreciate that fact for two reasons: (1) you can safely fire 223 in a firearm chambered for 5.56, but NOT the other way around; and (2) a firearm chambered for 5.56 will not fire 223 quite as accurately as one chambered specifically for 223. That said, a 5.56 rifle firing 223 ammo will deliver perfectly serviceable accuracy over all but the very farthest distances. (If you want the ideal chamber for both 5.56 and 223, please look into the 223 Wylde chamber.)
Now, as far as their efficacy for self-defense goes, the 5.56 and 223 are pretty much apples-to-apples the same. The 5.56 is the military/NATO round, whereas the 223 is the commercial cartridge – but they do not perform differently enough to recommend one over the other. What I would advise is that you focus on the bullet. You really want a bullet designed for terminal expansion if you would ever fire your rifle in self-defense, as terminal expansion (A) creates a more injurious wound channel, and (B) reduces the risk of over-penetration that could jeopardize an innocent bystander. Assuming your rifle is chambered for 5.56 (and therefore safely able to fire 223 as well), I would highly recommend this law enforcement grade ammo for home defense: luckygunner.com/223-rem-55-grain-nosler-ballistic-tip-federal-le-tactical-tru-20-rounds
Please let me know if my explanation begs any additional details!
