Best Barrel Length For 5.56: Science-Backed Guide

Introduction

I will take a gamble and say that you’re here because you are either building (or buying) an AR-15 or looking to buy an upper with a shorter or longer barrel.

Knowing which barrel length will serve you best (and won’t sacrifice too much) is vital information to understand.

Finding the right barrel length can boil down to a few different factors. One of those is how you plan to swing that barrel around. Is it around corners? Tight or Long? Or are you looking for something that will afford you a bit of range?

You see, it’s a rabbit hole. But it doesn’t have to be too hard to understand. That’s why we’re here (well, my cat and me), so you don’t have to look too far.

Let’s get into it before I lose you over here.

Side note: The barrel lengths are accompanied by the names and models of manufacturers who are the best in the barrel game. Now I’m not saying these are the only manufacturers who make kick-ass barrels, but this is a list from my experience and from keeping my ears on the street.

Best Barrel Lengths For 5.56 & Manufacturer Recommendations

If you don’t have time for the fun scientific experiments, here’s a short list to order your barrel (or rifle) before the sale closes.

Along with the barrel lengths, I recommend some manufacturers who make the best of the best barrels (in no particular order), in case you also want to know that information.

Best SBR Barrel Length – 10.3 Inch Barrel – Daniel Defense MK18 Mod

Best Home Defense Barrel Length – 14.5 Inch Barrel – Noveske Gen 4 Afghan Rifle

Best Mid-Long Range Barrel Length – 16 Inch Barrel – LWRC IC DI Standard

Best Long Range Barrel – 20 Inch Barrel – Knights Armament SR25

Best 5.56 SBR Barrel Length – 10.3 Inches – Daniel Defense MK18

MK18 Barrel For Sale

Pros & Cons

While 10.5 Inches is still too short to get the most out of the 5.56×45 cartridge, this barrel length is built for those pipe-hitters out there that kick doors down in the name of freedom.

Or those individuals (like me) who specialize in clearing their house when the wife and kids are away. We like to call it “Bathroom Ops,” and it’s very fun.

It also makes for a great home defense barrel length since adding a suppressor will still afford you the mobility to move around the house and cut around those corners like John Wick.

Center-axis relock, anyone?

I wouldn’t recommend a 5.56 for home defense if you live in close proximity to neighbors. Walls are thin, 5.56 penetrates, and too much penetration can lead to penetration in other places. If you get what I mean.

One great example of the 10.5 Inch barrel being an absolute beast is the older Daniel Defense MK18s. I’ve seen those rifles be put through hell and high water (literally) and still come out on top.

The newer models require Daniel Defense proprietary magazines to drop properly, and I also don’t have as much experience with those. I will only recommend what I know. They work with Gen2 P-Mags, but they don’t drop adequately enough for me to say, “Hey, go buy this, fine shooter.”

Of course, owning one of these would require a tax stamp. But it’s worth it. They also come with SBA3 braces if you want it in pistol configuration.

We talk about the differences between AR-15 pistols vs. rifles here.

Anyhow, you must understand that when you use a barrel length this short, you will NOT get the most out of the 5.56 round. You will also experience high muzzle flashes and some gassiness. While muzzle flash and gassiness can mitigate those with different gas systems and a suppressor, it’s still worth noting.

I ONLY recommend this barrel length for close-quarters engagements. Be wary, though; the muzzle flash on a short barrel will give away your position quicker than Pence gave up Trump.

As always, consider your needs. This isn’t the best SHTF barrel length.

The DDMk18 was also mentioned in our list of the best SBRs.

Best Home Defense Barrel Length – 14.5 Inch Barrel – Noveske Gen 3 Afghan Rifle

14.5” Barrels For Sale

Pros & Cons

And when I say Home Defense, I mean inside, where the family resides, and outside where you may have to preserve your land. You may have a coyote problem or live in Tacoma, Washington, and have other issues to worry about.

I like to consider the 14.5 barrel length as the best overall barrel length for AR-15s. It doesn’t sacrifice too much in ballistics and still lets you skirt around the corner without feeling like you’re pushing a musket around.

No, the 14.5 is Jesus’ length. If he carried an AR-15 against the Romans, he probably would have run a 14.5-inch barrel (with some quad-tube nods). Also, it most definitely would have been a Noveske.

Or a Knights. But most likely a Noveske. One of his homies would have carried a Knights, though.

Noveske has been known for making some of the most bad-ass rifles on the market. And their barrels are part of the reason why everyone wants one in their safe.

Well, that and their marketing.

But here’s the thing. Noveske uses barrel profiles from the M249, which has double the thickness in steel and the chrome lining inside. And it’s meant to run on a fully automatic machine gun.

Durability? Check. Accuracy?

Well, just how accurate is that barrel?

Sub-MOA if all the stars align.

Check.

After all, John Noveske did focus mostly on the barrel when making his rifles. It’s also how he started in the industry. Rest in Peace to that legend.

Best Mid-Long Range Barrel Length – 16 Inch Barrel – LWRC IC DI Standard

16” Barrels For Sale

Pros & Cons

If you want to get the most out of the 5.56 round, I recommend a 16-inch barrel. If you refer to the table in the Buyer’s Guide, you can see that the 16-inch barrel length is where things start to look really good.

The 16-inch barrel length is excellent for those of you who are going to be enjoying a bit of mid-long-range shooting. It can also work indoors, but I wouldn’t suggest it unless it’s your only option. In that case, send it.

One manufacturer who makes some pretty sick barrels in this length would be LWRC. Which was initially the rifle I was going with until I found my BCM, who I like to call Big Bertha.

Why do I recommend the LWRC barrel? Well, besides looking cool (all that matters), it’s fluted, cold hammer forged and treated with NiCorr. I’ll explain what that means.

It is more lubricious, heat-resistant, and corrosion-resistant than normal chrome-lined barrels. The fluting helps by giving the barrel more surface area, which slows down the heating-up process when you’re burning through magazines.

As for accuracy, I’ve seen about one to two MOA come from the other side. I wouldn’t recommend it for straight-up accuracy. It’s more for hard use.

Best Long Range Barrel Length – 18 Inch Barrel – Knights Armament SR30 

18” Barrels For Sale

Pros & Cons

I’ve spoken about my affinity for Knights Armament rifles in the past. When you build firearms for the U.S. Military for so long, you learn what it takes to build a rifle that outperforms the rest.

And barrels that are up for the task as well. Of course, for the price tag one pays to get their hands on a KAC SR30, you would hope the barrel is of good quality.

You get everything you want in a barrel that will run harder than my Army and Marine folks when they hear Retreat (if you know, you know).

Some sort of voodoo hammer forging and chrome lining sets Knight’s Armament barrels way ahead of most (if not all) barrels on the market.

I have heard of many fine shooters putting their SR30 Barrels through 80,000-90,000 rounds, suppressed and unsuppressed, before losing just a bit of MOA (accuracy). So I would say that makes the barrel pretty damn good.

If I can quote the venerable Garand Thumb, “Knights Armament must have done some Hocus Pocus or made a deal with a mage because no matter what, this barrel will hold sub-MOA all day long.”

And that’s the best way I’ve ever heard it said.

Now, most may say that 20 inches is better for long-range, but you won’t notice much difference. Trust me. Been there, done that.

How We Chose Our Top Picks

Well, for one, it had to be a barrel.

Nah, just joking fine shooter.

Aside from a bit of experience, we kept our ear to the street like Nelson Mandela and asked some gentlemen with extensive experience on the subject. A few armorers, a few of you fine shooters, and endless forums dating back to Jesus’ time.

In the end, this is what we came up with.

Are you not entertained?

Before You Swipe (Buyer’s Guide)

Ideally, you would look at this section before sealing the deal. Here we have a ballistics table and recommended lengths for specific uses.

The numbers on the ballistics table are variable and dependent on many different factors, such as ammo used, temperature, the condition of the barrel, and a bunch of other things. So take it with a grain of salt.

Let’s talk barrels.

What To Look For Before Buying Your Barrel

What you need and what the next guy needs are two different things. He may want to use his AR-15 for home defense, whereas you may want to hunt some warthogs that have been terrorizing your land for the past few months.

After all, do you really want to swing a 16-inch barrel around the corners of your apartment when something goes bump in the night?

Likewise, you don’t want to go hunting wild boar with an 11-inch barrel, either. With a round like the 5.56×45, you want to get the most out of it, with as minimal recoil as possible. And you only achieve that with barrel lengths of 16 or higher.

Gas system lengths are also important; we talk about that extensively in our gas systems length guide.

Getting The Most From 5.56

Okay, I’m going to make a table with some numbers in the name of science. Pay attention to how the feet-per-second changes as you shorten the barrel. You can see that it changes around 50 feet per second for every inch.

Sidenote: There are many variables that determine these numbers, such as the temperature, twist rate of the barrel, and grain of the ammo you are using.

For example, 55-grain with a 1:7 twist rate will give you different readings than 68-grain match ammo with a 1:10 twist rate. You feel me knocking, fine shooter?

What Are You Using It For?

Home Defense? Hunting? SHTF?

Either way, barrel lengths have been shortened or lengthened for their own reasons. And, to keep it real with you, I don’t recommend an AR-15 for home defense anyway.

Now now, I’ll tell you why.

Short-barreled AR-15s are louder than the old lady on your honeymoon. And the unburnt powder coming out of the barrel causes a flash. And not the kind of flashes we see in New Orleans. No, no, these flashes actually suck.

And they rob you of your sight. It’s like a flashbang going off right in your face. Not only is the intruder in your home, but now you’ve gone and nine-banged yourself.

Now your ears are ringing, you can’t see worth a damn, and the intruder has the money you were using to buy your wife an anniversary gift. And probably your wife.

I won’t even get started on over-penetration. We all know too much penetration is no good. Has to be just right—enough to get the job done but not more than you need.

This is doubly true if you live in close proximity to neighbors.

I would go with an AR-9. Which is an AR-style rifle that shoots 9mm. If you’re worried about penetration, the recoil is light. Aim for the heart, Ramon. Or the head.

But since this is a 5.56 article, I suggest getting a suppressor if you want to run 5.56 for home defense. I know it’s expensive and takes a while to get, but so does a new wife or new eardrums.

Is 5.56×45 Good For Hunting?

No matter what barrel length you choose, the round must be able to put the animal down easily. Especially if you’re out there hunting big game. Like bears. No, not black bears. Brown bears.

You know. The ones that run at you at about 35 miles per hour and will use your femur as a toothpick?

Yeah. Those guys. Now I’m sure many of you fine shooters have hunted different types of game both big and small, with 5.56/.223, but I wouldn’t take a shot at a brown bear unless it’s a broadside lung shot. And even then, I do not want to shoot at a bear with a 5.56.

5.56 hasn’t been known to be the best at stopping power. I’ve even heard stories of a feller over in Afghanistan who put 10 rounds of 5.56 into a guy, and the man kept coming. Eventually, he dropped.

Now imagine that against a grizzly. Sure, those guys in Afghanistan had enough drugs in their system to make a large horse do the pee-pee dance, but you still expect the round to do its job.

Against medium-sized game like deer, broadside shots always do the best when working with 5.56. Still, it does better against personnel rather than animals.

FAQs

Conclusion

Wow, you made it to the end of this arduously long article. Congratulations! And thank you.

I hope you found what you are looking for, and if there is anything missing, please let me know in the comment section.

As always, we recommend going with a barrel length that will serve you in more ways than one. Or, just go with which one makes you look the coolest. Because at the end of the day, looking cool is all that matters.

See you on the range, fine shooter.