First, for the purpose of this article, we’re going to talk about .223 and 5.56 as though they are the same cartridge. We know they are not, and that the 5.56 generates higher chamber pressures, but for all intents and purposes, they are effectively the same in terms of ballistic performance.
So, with that said, and knowing that the vast majority of AR-15 and AR-style platforms are chambered in 5.56, let’s talk about why this is the cartridge to beat, all around.
Consider this before you make your next build. You might want a 556 upper for it.
Low Weight
Say whatever you want about it, but 5.56 cartridges are light. Most weigh just a hair north of 12 grams, making them a true featherweight among centerfire cartridges. For reference, a 7.62x51mm NATO cartridge weighs more than 25 grams, making it twice as heavy. That doesn’t even scratch the surface of other, bigger, heavier cartridges.
As for that, the low weight means that it’s easier to carry more ammo. That means loaded mags will be lighter, too, which is a boon not only for the soldiers that carry them but for those that compete and hunt with them.
Small Size
This falls into a similar camp as low weight. These cartridges are about as small as centerfire rifle cartridges come, meaning both the rounds and loaded mags take up less space in a trunk, a pack, or a vest. That makes them easier to carry, too.
Affordability and Availability
Under normal circumstances, both 5.56 NATO and .223 Remington cartridges are not only affordable but downright cheap. We’re experiencing one of the worst ammo crises at the moment, and prices are still fair.
Most 5.56 cartridges will cost between 40 cents and a dollar, depending on what they’re loaded with, and the specialization of the bullet or cartridge. The wide availability of surplus ammo keeps costs down, too. The same can be said for .223, for its part.
Compare this to other centerfire cartridges which can also cost more than a dollar a round. Moreover, both 5.56 and .223 are usually widely available at shops around the country.
Low Recoil
Both 5.56 and .223 produce minimal recoil and in the world of centerfire cartridges, these rounds take the cake. If you want to shoot a lighter-kicking cartridge you more or less need to step down to rimfire.
This of course has several advantages. One is that it makes both 5.56 and .223 excellent centerfire cartridges to introduce new shooters to the sport. It also means it’s easier to make quicker, more accurate follow-up shots and to shoot for longer with less fatigue.
Reloading Costs
Because the .223 and 5.56 are both so widely available, so too are reloading components including bullets, brass, powder, and primers. With that said, they’re in somewhat shorter supply right now than they have been in the past, but they are still readily accessible and fairly affordable.
5.56 Performance
Here’s what you may not know about the development of the 5.56x45mm NATO. It was requested by the Army Ordnance Department to replace the .30-06 that was fired by the M1 Garand, but it was required to have similar accuracy and ballistic performance out to 500 yards, while producing similar wounding capabilities to .30 Carbine ammunition.
The Army also wanted a cartridge that was lighter and smaller, enough that a rifle with a 20-round mag would weigh 6 pounds or less. It was also required to deliver adequate ballistic performance to pierce a US M1 Helmet through one side at 500 yards and 3.43mm steel plate at the same range.
For a .22 caliber bullet, that’s not too bad at all.
As a Defensive Cartridge
At the muzzle, 5.56 NATO can produce muzzle energies in the area of 1,100 ft-lbs. This is nearly 3 times the energy of 9mm and over twice the energy of .45 ACP, two popular handgun cartridges used for defensive purposes.
As a rifle cartridge, it is excellent for defensive use, especially when loaded with hollow and soft-point bullets, although at very close ranges, overpenetration can definitely be a concern. Power, however, is not.
As a Competitive Cartridge
Because it is low cost, available, light, and produces little recoil, 5.56 makes an excellent cartridge for competition, pretty much for all of the same reasons that it makes sense as a defensive cartridge.
As a Long-Distance Shooting Cartridge
Both 5.56 and .223 are very flat shooting cartridges. Are there other, better long-range cartridges? Absolutely. Just look at the .220 Swift.
But, all the same, 5.56 and .223 shoot fairly flat, both dropping roughly 57” at 500 yards. Compared to the .308’s drop of 66” at 500 yards, you can see the difference.
Again, there are better long-distance cartridges but for target purposes, you could do worse than .223/5.56.
As a Hunting Cartridge
There are some that will tell you that 5.56 just doesn’t have the power to be an effective hunting cartridge, but this is not true. It is exceptionally versatile.
For one, it shines as a varmint round, even though it might be a little too powerful for that, and is tops for predators like coyotes and foxes.
It can also take medium-sized game at close and intermediate ranges with proper shot placement - like deer. Just make sure you stay within your state’s legal calibers.
And, again, it is fairly affordable.
If That Weren’t Enough, Plain Old Americans Helped with Development
One last reason to love the 5.56 is that good old American civilians helped develop it. The Army Ordnance Department actually enlisted the help of regular civilians to help make the first cartridges. What other cartridge can say as much?
Invest in a High-Quality 556 Upper for Your Next Build
If these reasons aren’t enough to renew your interest in the 5.56x45mm NATO, we don’t know what will.
At any rate, reason must have reached at least a few of you. For you, we offer a wide range of 556 upper receivers. Some of them are complete, assembled AR-15 uppers with charging handles, BCGs and gas systems installed, making your build easier.
Take a look through our selection of 5.56 uppers and get in touch with us at Sales@MCSGearup.com if you need any assistance.