We’ve gone over AR-15s and AR-10s a lot here, but what we’ve never done is compare the two.
These rifles are integral not only to firearms and military history, but also to each other’s development, and the story behind them is one of the most interesting parts of firearms development in the Western world.
Hopefully, if you’re trying to decide which one you want, or just want to know what the difference is between the two, this will help.
What exactly is the difference between the AR-10 and the AR-15?
Why would you choose one over the other?
I’m so very glad you asked. Let’s get started.
The Birth of the AR-10
Early in the 1950’s, the Fairchild Aircraft company began work on designing what would go on to become the first of the “AR” line of rifles, the AR-1. Called the “Para-Sniper,” this rifle was designed as an upgraded paratrooper weapon and was meant to be light, relatively short, and easy to jump out of a perfectly good airplane with. 25 were produced.
Shortly thereafter, the company created a subdivision that would go on to become known as Armalite. Armalite, being far too small and underfunded to become a major player in the arms manufacturing world, was instead focused on prototyping advancements to existing weapons platforms that could then be sold as designs to large manufacturers.
Months later, George Sullivan, the founder of the Armalite company, was testing a version of the follow-up to the AR-1, the AR-5 survival rifle, which was meant to be used in survival situations by airmen who had been shot down, particularly in remote locations or behind enemy lines. This rifle would go on to become the popular AR-7 survival rifle still made today.
While at the local range for the testing, he met Eugene Stoner, a small arms designer and the rest, as they say, is history.
Stoner would go on to serve as Armalite’s chief engineer and during his tenure would develop the rifle we now know as the AR-10, as well as the AR-15/M16 later on.
The 7.62x51mm AR-10 he developed first was submitted to the US government as a replacement for the M1 Garand, but ultimately lost out to the Springfield Armory M44E4, the rifle that would go on to become the M14.
Despite this setback, Stoner and Armalite continued to refine the AR-10 concept, including replacing the aluminum/steel composite barrel (a George Sullivan addition that Stoner strongly opposed) that failed dramatically during torture tests and killed the rifle’s chances at early adoption.
The Birth of the AR-15
Following the relative failure of the AR-10, Eugene Stoner and other engineers including Jim Sullivan decided they weren’t through yet, and began work on a smaller .223-caliber rifle to submit to the CONARC (U.S. Continental Army Command) testing meant to replace the Browning Automatic Rifle, M1 Garand, M1 Carbine, Thompson Submachine Gun, and M3 “Grease Gun” all with a single rifle.
Despite performing well in an admittedly very difficult challenge, Armalite’s submission, the .223-chambered AR-15 was vetoed by Army Chief of Staff General Maxwell Taylor in favor of the M14. This was despite the AR-15 proving to be three times more reliable than the M14 and one AR being worth two of the larger rifles in terms of firepower and carriable ammunition.
Frustrated with this setback and dealing with some major funding issues, Armalite closed the doors on it’s machine shop and sold the designs of the two weapons to Colt, who then immediately moved the charging handle of the AR-15 back to the end of the receiver as it was on the original AR-10, and geared up to mass produce the rifle in large numbers, something that would prove key to the success of the rifle later.
Eventually, after some success in smaller markets, General Curtis LeMay, Vice Chief of Staff of the Air Force at the time, ordered a number of AR-15’s primarily for pilots to have a fighting chance if shot down, echoing the AR-1’s original design intention.
In 1961, LeMay was promoted to Chief of Staff of the Air Force, and requested an additional 80,000 AR-15’s to arm his personnel with, finding the lighter and lighter-recoiling smaller-caliber rifle to be much preferable and effective to the larger M14 in service at the time.
Meanwhile, the Army’s continued testing of the AR-15 found that the .223/5.56 rifle was much easier to shoot (especially in full-auto) than the 7.62mm M14. That same year, the Army found that 43% of shooters with the AR-15 qualified Expert in marksmanship trials compared to 22% shooting expert with the M14.
Despite all of this, and seemingly determined to be on the wrong side of history on the issue, General Maxwell Taylor, now Chair of the Joint Chiefs of Staff, again vetoed the AR-15, claiming that having two differently-chambered rifles in service at the same time would be problematic.
Taylor and LeMay would continue to clash over the issue, especially when it became evident that the AK-47 was vastly out-performing the M14 in the early days of the Vietnam War.
However, after the M14’s production was halted due to an inability to meet demand, LeMay finally got his way after it was decided that only the AR-15 could be produced in significant quantity to arm all branches of the military for the rapidly intensifying conflict in Vietnam at the time.
Colt’s heavy backing of the platform and massive manufacturing output capabilities would thus save the rifle, and change the course of history forever as intermediate-cartridge rifles that allowed troops to carry hundreds of rounds of ammunition easily would become the norm, and in the case of the AR-15 itself, would birth a rifle to rival the popularity of the still-ubiquitous AK-47.
Following some minor tweaks, including the addition of a forward-assist that the United States Airforce, legendary weapons designer Eugene Stoner, and your humble gun scribe here all find to be a useless expense, the rifles Colt produced to meet the needs of the military would go on to become the M16 which, despite some early issues, would go on to clash with Kalashnikov’s best work not only on the battlefield, but in overall popularity as the design of choice for military rifles the world over.
You can check out the full history of the M16 for more information.
Modern AR-10s, whether produced as “Armalite-style” or the latter “DPMS-style”, are all really just scaled up versions of the AR-15’s that were produced by Colt. These rifles are still commonly used on the battlefield today, but they are also massively popular in the civilian market (in America at least) in semi-automatic variants.
Unlike the original design, which was only chambered in 7.62×51, modern AR-10’s come in a variety of “long-action” chamberings including the increasingly popular 6.5 Creedmoor.
These AR-10s see use many places today, particularly by long-range shooters, whether they are hunting enemies on the battlefield, wild game, or just a higher score at the range.
Be sure to read about the best of the modern AR-10s if you want to know more about how the rifle has evolved.
Modern AR-15s are made by…just about everyone with a machine shop, it seems like. Despite new advancements such as piston-driven gas systems to replace the original direct-impingement system, the design has remained mostly unchanged this whole time. You can see the full list of internal AR-15 parts for more information.
What has changed, is the calibers on offer. Much like the AR-10, the AR-15 is available in a wide variety of chamberings from the original 5.56mm/.223, to modern chamberings like the 300 Blackout and 6.5 Grendel special-purpose cartridges.
Note: Be sure to check out our look at the exciting new .224 Valkyrie cartridge.
Why Choose an AR-10?
So, if the US military picked the intermediate chambering of the AR-15 over the big 7.62x51mm chambering of the M14, wouldn’t it follow that it would be better to choose an AR-15 than the AR-10?
If you’re looking to get the best accuracy and power at long distances, or just need a lot of stopping power in general, the AR-10 may be your best bet.
Sure, there are options for the AR-15 that are purpose-built to do more damage at range or stay super-sonic longer for better accuracy, but these options are often chosen because the rifle they are fired from happens to be lighter, cheaper, and more supported by the firearms industry.
If you truly need the extra power and accuracy at the range or need something that’s going to impart the maximum amount of force to a target at any range, the AR-10 may be the better choice.
Personally, I like the AR-10 better for those long shots, or if I’m hunting dangerous game up close. I’ve talked before about my noted dislike of wild hogs. My hog-hunting guns are a lever-action in .45-70 and an AR-10 in 7.62. I’ve never doubted that either will stop a charging 250lb boar with a single shot, provided I do my part.
Not that I especially enjoy having to make that particular shot. But I have made it on two occasions, both with the AR-10. I also missed it on one occasion that ended up being a very close encounter.
In that scenario, I was incredibly glad for the rifle’s fast follow-up shot potential. There’s a reason lots of SF folks choose 7.62mm battle rifles for when every shot counts in a close-range situation.
My precision long range gun is also an AR-10, and while it’s not as accurate as some of the finely-tuned bolt guns out there, it’s also not nearly as expensive.
I’ve also accepted 1st place prizes when competing against some of those bolt guns, which just goes to show that, in the right hands, the AR-10 can still run with the big boys when it comes to accuracy.
Why Choose an AR-15?
Not everybody needs that extra range or stopping power though (or the extra expense). If you’re looking for a good rifle that can still hit what you point it at, and do it over and over again without breaking the bank, the AR-15 is an excellent choice.
It’s still a lighter-recoiling, easier to shoot, cheaper to shoot rifle that is, right now, being used on battlefields across the world in one select-fire variant or another.
The AR-15 is also (arguably) the most popular gun platform in the world, and if it isn’t, it’s second only to the AK-pattern rifles that came to market a little earlier and therefore had an unfair head start.
What does that matter? Well, go to any gun store or even your local Walmart and you’ll find ammo for your gun. You’ll also, depending on the current political climate, find parts, magazines, accessories, and other copies of the rifle itself.
That level of aftermarket support also means you can do just about anything with your rifle, from hunting to building a recce rifle to home defense. And you can reconfigure your gun on the fly, with minimal tools or gunsmithing experience.
This makes the rifle a great purchase for shooters who need one gun to do it all, which is something the AR-15 really excels at, especially once you realize you have access to a wide variety of calibers and cartridges just by swapping out the upper assembly.
It’s also easy to build either of these rifles, but it’s a lot cheaper to build an AR-15 provided you have the right tools on hand.
Or, do what I did, and get both. Both rifle styles are absolutely amazing if used for their intended purposes, and neither will disappoint. I’d say if you can only get one, go with the AR-15 because it’s easier to shoot and cheaper to feed and maintain. If you want one to hunt with or make shots past 800 meters, go with the larger-caliber AR-10.
If you have the money, get both. You won’t regret it.
What do you think of the AR-10 and the AR-15? Do you own one or are you thinking about pulling the trigger (pun intended) on a purchase? Let me know in the comments below.