There are a lot of choices to make when you decide to build a new AR. Pick a stock configuration, a trigger weight, do you want a slick side upper or are you a diehard fan of the forward assist? From pistol grips to takedown pins, every part presents a choice, but what about barrels? If you’re trying to decide if you want to go with a 5.56 AR barrel or a .223 barrel. For those on the fence, the differences between the .223 and AR-15 5.56 barrel might not be readily apparent. Those lines get even more blurred with the tweaks AR-15 barrel manufacturers make in the name of improved performance and longevity of service life. Wing Tactical wants to help you choose the best barrel for your build, so we’re here to broaden your knowledge of the AR-15 .223 and AR-15 5.56 barrel families.

What’s the Difference Between the .223 and 5.56?

On the surface, the AR-15 .223 barrel and the AR-15 5.56 barrel look very much alike to the untrained eye. The difference in the pedigree isn’t apparent until you dig a little deeper. On the surface, the two favorites of AR-15 barrel manufacturers look very much alike. In fact, the case dimensions are identical. You can get either version of the AR-15 threaded barrel from quality manufacturers but you should take the time to consider what you're really buying.

Sure, we know that the .223 Remington is more likely to be a "precision" civilian-oriented round, and the 5.56 NATO is a Mil-Spec type round, but upon closer scrutiny, the differences between the two are more than just those of origin. These barrels are all about the chamber and its capabilities. The 5.56 and .223 might be on the same bus, but they got on at different stops and they’re not about to get off at the same destination either.

.223 AR-15 Chamber: Born and Bred for the Civilian Market

The .223 Remington chamber is a SAAMI chamber. What that means is that the specs for .223 chambers and therefore .223 barrels are outlined by The Sporting Arms and Ammunition Manufacturers Institute. SAMMI Specs aren’t created to allow great margins for variation in ammunition, and won’t necessarily be failsafe for the “it must be close enough” reloader. Treating the .223 Remington that way is sure to lead to significant trouble. 
The .223 Rem chamber is tighter, allowing for increased accuracy, but this means that there’s less room for the case to expand upon firing. That can create a number of different issues, none of which will improve your mood when they happen whether you’re at the range or afield when they become your problem at the moment. Let’s have a look at a couple of the problems that occur when 5.56 cartridges are fired in a 223 barrel chamber.

Increased Pressure Blows Out Primers

Any of you who have been taught to look at the character of a firing pin mark on a primer to gauge if a load is pushing the limits in sport rifles will be mortified at this one. Yes, the primer can and will, with some frequency blow out into the receiver when a 5.56 cartridge is fired in a .223 AR-15 chamber. Aside from being a serious warning sign, a primer roaming loose in your chamber or bouncing around in the top of a mag has the potential to create more havoc in the form of failure to load or fire as is can create a jam or block moving parts as the rifle attempts to cycle.

Case Expansion Can Cause Failure to Eject and Worse

The greater pressure created by the hotter 5.56 load causes greater case expansion than that seen in .223 rounds that case expansion teamed with the tighter dimensions of the .223 barrel can be problematic, causing cases to stick in the chamber, some even requiring a rod pushed back through the barrel to get them loose. In addition to failure to extract, in extreme instances, over-pressure in the chamber can even cause damage to the upper receiver, which isn‘t just costly, but can prove dangerous to the shooter and nearby onlookers.

5.56 NATO the Tactical Cartridge made for the M4 & M16

First things first, let’s address the big picture here. Military rounds are a very different breed of cats from their civilian counterparts. While accuracy isn’t entirely an afterthought, the foremost consideration for military use is reliability. That means the design of a Mil-Spec chamber has different criteria than those of a chamber marketed for sporting use.

The 5.56 AR-15 is Different Under the Skin

Military rounds are “hotter,” that is, they run greater pressure than their SAAMI counterparts so that they fire reliably and push a stable projectile with a minimum of fuss in a variety of conditions, many of which you wouldn’t even take your favorite range rifle out in. Even 5.56 NATO cartridge itself isn’t the same as the .223 Remington. While the external dimensions are the same, the thickness of the cartridge walls is greater in the 5.56. This helps the 5.56 handle the higher pressure of its hotter load and makes it durable even under the abuse of active maneuvers.

The 5.56 Forgives

Unlike the .223 chamber, the 5.56 chamber features a deeper throat, allowing for easier extraction of unfired ammunition, something the .223 can have issues with. Occasionally, these chambers will even retail the bullet from an ejected cartridge. It’s no fun to have live powder spilled in the receiver as well as into a loaded magazine. Oh, and then you can push that bullet back out with a rod because it’s not coming out on its own.

While the standard AR-15 .233 barrel is quite tight (though not as tight as a match grade .223 chamber) the 5.56 AR barrel chamber is a bit larger and much less prone to retaining fired cartridges. That’s a pretty big deal in the tactical environment and can be a major plus for those of us who reload and might occasionally come across a case that’s a little oversized.

So What’s All This Mean?

Well, it means that the two chambers and cartridges are not interchangeable and those who tell you they are shouldn’t be trusted. Unfortunately, a pretty significant number of manufacturers have sent out barrels and complete AR-15s marked with .223/5.56 AR-15 barrels as if they are the same thing, and it can be difficult to know what to order when you’re only looking at one AR-15 for your collection. Your best bet is to look carefully at your own situation and make a conscious decision to choose the correct version of the AR-15 for your purposes.

OCD Loves the .223

If you're fastidious about keeping everything just right, the .223 might make your happy as a clam. For those of us who like options and forgiveness, the 5.56 chamber is a little more our style. You can indeed, fire a .223 through a 556 barrel and come out none the worse for the experiment. If preparedness is your thing, or you’re concerned about future access to ammunition, the 5.56 is your baby. Say there’s a shortage of the specific ammunition your AR-15 is chambered for. If you own and .223 AR-15 barrel, you’ll have to put it on the shelf until the proper ammunition is available. If you ordered the Mil-Spec 5.56 barrel despite the protests of your uncle Jack who insists you’ve chosen an inferior piece of equipment, you can still go in his garage and swipe a box of .223s and continue as planned. Uncle Jack will have all sorts of things to say about accuracy, but you always could out-shoot him with a BB gun so chances are you’re in no danger of losing to him now.

Where to Source Your 556 Barrel or the 223 AR-15 Barrel of Your Dreams?

Whether you're looking for an AR-15 threaded barrel in .223 or a 5.56 fluted barrel, there's sure to be someone out there making exactly what you're looking for. So if the manufacturers aren't always transparent about the difference between the .223 and 5.56 and might label the barrel with a slash instead of a definitive description, how do you know what to buy?

Make it simple to find the 5.56 fluted barrel or the AR-15 threaded barrel of your dreams by using a trustworthy source for all of your small arms parts and accessories. A company like Wing Tactical can help you choose the AR-15 .223 barrel you need for marksmanship or the 5.56 barrel that will take you through any tactical challenge. The customer service reps at Wing Tactical actually know the difference between a .223 and 5.56 chamber and can help you make an informed decision before you buy the 5.56 fluted barrel for your self-defense weapon.

Wing Tactical only stocks barrels from the finest AR-15 barrel manufacturers. You won't find a 556 barrel in our catalog that isn't what we present it as. Be confident in your choice, whether it's a 5.56 AR barrel for a field rifle, or a .223 barrel for a long range target rifle, Wing Tactical has what you need. If you're not sure which way to take your build, we can help you find the right parts and accessories without wasting your time or money on things you don't want or need. Choose Wing Tactical for your 5.56 or .223 AR-15 barrel and give yourself an edge.