Far and away, uppers in 5 56 NATO are the most popular assembled options for tinkerers and home builders that customize, or even make their own rifles entirely.
And it is an excellent cartridge with a lot of versatility and plenty of use cases. Given certain conditions, it is excellent for training, high-volume target shooting, long-range shooting, competition, hunting, and even defensive applications.
It has many more selling points than these, even - but there are limitations to the cartridge, and there are times when you might want to consider something other than an upper in 5 56. Here are some of them.
You Need More Power
The 5.56 NATO is a solid flat shooter and packs decent power, generally in the area of 1,200 to 1,300 ft-lbs of muzzle energy, depending on load data, including bullet weight, and barrel length.
But this is objectively pretty low as far as rifle cartridges are concerned, and unless you’re punching holes in paper or ringing steel, power counts.
There are plenty of other, more powerful rifle cartridges around which the AR has been reimagined, as well as assembled uppers so you can capitalize on them.
The long and short of it is this. If you need a more powerful cartridge, whether for close-quarters defensive uses or for hunting, there are many better cartridges than 5.56x45mm NATO.
Weight and Space Aren’t a Concern
Two of the biggest selling points of 5.56 NATO (and .223 Remington) are that it is compact and light. This makes it easy to carry in the field, and easier to pack more of it, diminishing fatigue.
But for benchrest shooters, who cares? Or if you only keep the rifle to protect the castle, why should this matter? In the latter case, there are more powerful cartridges that arguably produce less of an overpenetration risk, anyway.
So this breaks down some of the fundamental benefits of 5.56 to begin with - and makes other builds, not just those with uppers in 5 56, attractive.
You’re Looking at Short Range, Not Long-Range Performance
Without a doubt, 5.56 is one of the best long-range shooters out there, because the bullet drop is minimal and because it experiences comparatively little wind drift.
But, beyond accuracy at greater ranges, if you’re expressly looking for power at closer ranges, there are potentially far better options.
Consider an AR built in a pistol caliber, such as an AR pistol in 9mm. These are much more suitable at close range, and those they produce less stopping power, also produce less of a risk of overpenetration.
Then you have other calibers like .300 Blackout, 7.62x39mm Soviet, and of course .50 Beowulf that are just far better at closer ranges.
When Cost Doesn’t Matter
Another thing that makes 5.56 highly appealing is the comparatively low cost of the cartridge. Since these are loaded en masse for the military, a whole lot end up in surplus depots every year, destined for the ammo cans of civilian shooters.
With that said, if you are a hunter, only shoot in certain competitions, or keep for defensive purposes only, the per-unit cost of the cartridge may not matter much to you. What may matter much is performance. Sometimes that comes at a premium, and you just have to pay it.
When You’ll Be Reloading Anyway, So Availability Hardly Matters
On the same note - availability - if you’re not much concerned with it since you’ll be reloading, say, if you shoot a rifle with a .350 Legend upper, then it might not matter to you not only what the per-round cost was, but whether it was available at all.
Learning how to reload will open doors for you that will remain shut for others when certain calibers become scarce or pricy. That alone, in its own right, is enough good reason to learn how to reload.
What Other Calibers/Cartridges Might Be Better?
There are many calibers and cartridges that offer distinct and unique advantages over the 5.56 and .223. If you want a suitable alternative to an upper in 5 56, consider:
- .300 Blackout uppers: The .300 Blackout offers superior muzzle energy to the .223 and 5.56, and you can use most of the same parts for a 5.56 rifle with a .300 BLK rifle, except the barrel. In fact, even 5.56 cartridges can be necked out and loaded with .300 BLK bullets. This cartridge is superior for close-range engagements and hunting medium game at close to medium ranges.
- .350 Legend uppers: The .350 Legend, which shoots a substantially heavier bullet than a 5.56, produces considerably higher muzzle velocity, but that is not where the true draw lies. Building with a .350 Legend upper will give you the ability to hunt in states that have straight-walled only restrictions.
- 62x39mm uppers: Like .300 BLK, a rifle with a 7.62x39 upper has a lot of advantages over a rifle with a 5.56 chambering. It produces greater muzzle energy and stopping power at close ranges, although it lags a little at ranges beyond 200 yards.
- 5 Creedmoor uppers: The energy of 6.5 Creedmoor is superior to the 5.56 at nearly any range, and it is also an excellent long-range cartridge. Here’s the thing; if you use it for target shooting, you can save a buck with 5.56, but if you’re hunting at extended ranges, 6.5 Creedmoor takes it.
- 9mm uppers: There are some uppers, especially AR15 pistol uppers, in unconventional and even pistol chamberings. If you can find one with a 9mm upper, you’ve got one that offers solid performance at close ranges without too much risk of overpenetration.
What About Short Uppers (5”)?
If you’re looking at AR pistol builds, then consider a rifle with a short upper. Some of these are still uppers in 5 56, but they offer greater maneuverability and concealability, regardless of chambering.
Starting with an Assembled Upper Here
Getting ready to start your AR build? Consider an alternative to an upper in 5 56 and get it here. We carry a wide range of assembled, complete upper receivers in a variety of chamberings, along with all the parts needed to completely customize a rifle while building it from the ground up.