The AR-10 and AR-15 — What are the Differences?

Del Ton AR-10 sitting on a tan hardcase

When Dr. Dave Dolbee and I discussed this article, the wheels in my mind were whirling. I have used each platform, find both to be great guns, and think everyone should own more than one of each. However, the how and why I came to this conclusion need to be explained.

As far as handling and ergonomics, each is brilliantly designed and the function is the same. Some new shooters may not realize that the AR-10 7.62x51mm rifle came first. This .308 rifle competed with the FN FAL and M14. In the end, the rifle was downsized into the .223 caliber AR-15.

The primary difference between the rifles is the caliber. The AR-10 is chambered for the .308 Winchester or 7.62x51mm NATO. The AR-15 chambers the .223 Remington or 5.56mm NATO cartridge. There are others, but the big ones, such as the .300 Short Magnum, must be chambered in the AR-10. The .308 replaced the .30-06 as a sniper and machine-gun cartridge, and still serves today.

There are also many M14 rifles serving. The rifle has been referred to as shoulder-fired artillery overseas, compared to the .223. To the best of my knowledge, there are no AR-10s in military service. The .308 usually has a 1:11-inch twist; the .223 in modern rifles may feature a number of twists, but 1:8 seems most common. Both (usually) feature a 16-inch barrel.

The AR-15 was a response to the Russian AK-47 we encountered in Vietnam. The lighter AK was controllable in automatic fire and more ammunition could be carried than the M14 allowed, putting our soldiers at a disadvantage. President Kennedy ordered the AK-47 tested against the AR-15. The rifle was controversial and early versions suffered due to the powder combination used in the initial ammunition issued.

The rifle continued to serve and was developed into the present AR-15/M4 rifle. The new AR-10s are usually a 1.5 pounds heavier than the AR-15 and about three inches longer, due to the heavier receiver and longer stock. The AR-10 fires a stronger cartridge with more momentum, so you could not simply re-barrel the AR-15.

The bolt, bolt carrier, and springs must be heavier to accommodate the .308 Winchester. The AR-15 may accept a 20- or 30-round magazine, the AR-10 usually deploys a 20-round magazine. The decision is—do you wish to deploy a heavier rifle that is more powerful, or to maintain the AR-15 rifle—which is plenty powerful for most choices.

If you hunt medium game, the .308 is the better choice by far. It is effective against deer-sized animals well past 200 yards. You will get into a solid position and take the shot. If you are varmint hunting, the .223 AR-15 is the better choice. You may be firing more quickly in rapid movement. For personal and home defense, the AR-15 is the better choice based on ease of control and modest penetration in a home defense situation.

The .308 has greater wound potential, knockdown power, and penetration. At close range, the .223 is designed to fragment. A 55-grain bullet at 3,200 fps produces a tremendous wound. The problem, as velocity slows the rifle becomes less effective. The rule of thumb is the .223 loses much of its effectiveness at 100 to 125 yards. The .223 is very effective at close range with the proper loads, especially with multiple shots. The .223 will carry more ammunition for equal weight. The .308 is the better choice for designated marksman rifles intended to be used past 100 yards.

When you get down to brass tacks, the difference between the two rifles boils down to the caliber and the intended mission. The AR-10 is more powerful, heavier, and holds less ammunition. The AR-15 is lighter and holds more ammunition. Inside of 100 yards, the .223 is plenty effective on man-sized threats.

Ammunition is cheap and plentiful for the .223, and there are more ammo choices. For personal defense—9 times out of 10—the AR-15 is the better choice. For those living on the plains or needing a good hunting rifle that may double in the area defense role, the AR-10 is a great choice.

As for accuracy, there are true tack drivers in either configuration. I have not fired a dog in either that I can recall. As far as reliability and functionality, this is more a product of the ammunition, how clean it burns, and shooter maintenance.

Effectiveness for Home and Area Defense

.223 loads expand or fragment, producing wounds that result in immediate cessation of hostile action. This makes for a safer load for home defense. The .308 may punch through a threat, while doing less damage. While there are modern, purpose-designed .308 loads that produce good wound ballistics, the .223 remains the load of choice at shorter range. The .308 is the long-range rifle.

There are interesting things going on in either variation. As an example, the .224 Valkyrie, as developed by Federal Cartridge Company, is giving AR-15 fans an option that may shooter flatter than the 6.5 Creedmoor. Time will tell which will be more popular in the future.

At present, the AR-15 is far more numerous. The AR-10 has a loyal, but smaller, following. Carefully study your needs and choose well. There are well-made rifles among each type that serve a real purpose.


Do you prefer the AR-10 or AR-15 for personal defense? Which model is your favorite? Share your answers in the comment section.


About the Author:

Bob Campbell

Bob Campbell’s primary qualification is a lifelong love of firearms, writing, and scholarship. He holds a degree in Criminal Justice but is an autodidact in matters important to his readers. Campbell considers unarmed skills the first line of defense and the handgun the last resort. (He gets it honest- his uncle Jerry Campbell is in the Boxer’s Hall of Fame.)

Campbell has authored well over 6,000 articles columns and reviews and fourteen books for major publishers including Gun Digest, Skyhorse and Paladin Press. Campbell served as a peace officer and security professional and has made hundreds of arrests and been injured on the job more than once.

He has written curriculum on the university level, served as a lead missionary, and is desperately in love with Joyce. He is training his grandchildren not to be snowflakes. At an age when many are thinking of retirement, Bob is working a 60-hour week and awaits being taken up in a whirlwind many years in the future.

Published in
Black Belt Magazine
Combat Handguns
Rifle Magazine
Gun Digest
Gun World
Tactical World
SWAT Magazine
American Gunsmith
Gun Tests Magazine
Women and Guns
The Journal Voice of American Law Enforcement
Police Magazine
Law Enforcement Technology
The Firearms Instructor
Tactical World
Concealed Carry Magazine
Concealed Carry Handguns

Books published

Holsters for Combat and Concealed Carry
The 1911 Automatic Pistol
The Handgun in Personal Defense
The Illustrated Guide to Handgun Skills
The Hunter and the Hunted
The Gun Digest Book of Personal Defense
The Gun Digest Book of the 1911
The Gun Digest Book of the 1911 second edition
Dealing with the Great Ammunition Shortage
Commando Gunsmithing
The Ultimate Book of Gunfighting
Preppers Guide to Rifles
Preppers Guide to Shotguns
The Accurate Handgun
The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

Comments (18)

  1. I have had both and enjoy them equally in different situations. I have sold all of my true AR-15s and only hold on which is not a true AR platform from my understanding. It is the Sig 5.56 chambered in .223 rem and/or nato 5.56 mm. It does however accept all AR mags and that makes it easy to find mags. Getting to my Bushmaster AR-10 has been great and I actually put a medium powered scope on it so as to use beyond 150 yards if needed and my groups stay fairly close and 150-200 yard range. Again I love them both and like some people here reccomend both for your arsenal. If you are on a budget and can’t get both or it will be a while before you can get both then go with AR-15 in the .223 or like I did the Sig556 chambered in .223

  2. I have several AR15’s and an AR10. I’m an avid deer hunter and my AR10 has replaced my 30-30 and .270 as my white tail rifle. I really think that the .308 is as close to the perfect caliber there is,esp.hunting in Texas.

  3. I shoot both. Either one is excellent. I use the 15 for varments and target shooting. I use the 10 for white tail deer. I have downed deer beyond 250 yards. Both are very dependable.

  4. I dont agree with the statement the 5.56 is only good out to 125 yards. I have an ar pistol with 10.5″ barrel and can regularly knock down a 12″ plate at 235 yards.

  5. I built, what I consider, a high end AR 10. I wanted a medium range paper puncher essentially. I was disappointed. I expected moa or better. Didn’t get it.
    Then I built a .458 socom for fun. Realizing there would be no joy with that unless I started reloading. I started reloading.
    While I had plenty of .308 ammo, I thought “golly gee”, maybe I’ll load some myself and just see. Bingo! I had my sub moa punch.
    I love the thing. Too heavy to be practical at about 15 lbs, but lots O fun.

  6. Have both colt mt 6400 and windham ar10 in .308..The ar15 is my home defence. The ar10 in 308 with shooting sticks is s meat killer
    JS Texas

  7. I bought two AR-15’s a Daniel’s Defense and a Colt, I bought one Armalite AR-10, the metal magazine version now they take PMags (Mine does not accept PMags but I have plenty of the metal ones). Since I have built six AR-15’s, two AR-15 Pistols, one AR-9 Pistol, and 2 1/2 AR-10’s (One is not done)I will give my Son two of the AR-15’s and two AR-10’s as I have more than I need. I use AR-15’s for Fun and Home Defense. I have little reason to keep an AR-10, but I will.

  8. I cant stand the 5.56 which is only marginally better than the .223. I much prefer my .222 ar 15 as it is actually accurate at any distance I want to shoot out to about 450 yards. the .308 in my opinion is the BEST all around round you can carry it will kill at 5 yards or 500 with a single shot any animal in north America except a grizzly or its close cousins. as for capacity its not legal to carry more than 5 rounds to hunt game animals and if you are hunting pigs I think you are doing PDG to get 10 to 15 rounds off before the sounder is gone. That is as long as your not spraying and praying (If you do that you should not be using anything smaller than a .50 to reduce target suffrage.

  9. The US, from what I’ve read, never actually implemented the AR-10 into service. Of course, that’s AR-10, as licensed by Armalite. However, I do know that the US miilitary (specifically SOCOM) started adopting it a long time ago. So while the actual AR-10 is not in service, the SR-25 by Knight’s Armory has been.

  10. I have bought or built 4 AR platforms. 2 are 223/5.56 , one is 300 aac and the last was a stripped LR 308… I love them all. I don’t hunt much anymore and PA had just legalized 223/5.56 in semi to hunt small or varmint. They balked on big game like deer with a semi AR 308 cal. So for now, it build, change and reload to punch holes at the range.

  11. Sadly, it seems the United States will have to relearn the need for a weapon that actually kills reliably with a minimum of shots. It does little good to have a cheap round that requires multiple hits and has little penetration on barriers. There is little wonder the M-4 mysteriously became in vouge after our troops went to Afghanistan and Iraq.

    1. So your trying to kill your neighbors and the perp that broke in? Choose the right combination of rifle, caliber and ammunition type for the job.

  12. Clarification.

    The first of the .22 High Velocity Rifle rounds Developed at Frankford predated WW2, and postwar the .22 Frankford Light Rifle round, the .224 Winchester and the latecomer .222 Special rounds were developed to share the high velocity effective shock wave destruction of tissue.

    In 1957 a decision for the required longer effective range so the .22 FA Light Rifle round and the .224 Winchester rounds were chosen for further development.

    The round was NOT developed in response to the AK round, the US high velocity .22 project testing began before WW2 but the barrel steels were not suitable at that time, Development returned after WW2, the .224 Winchester Light Rifle being the leading contender. However, in testing, the late comer in the strange looking rifle using the .223 Remington round (a renamed .222 Remington Special) outperformed the .224 Winchester round in accuracy and ejection pattern issues. Simply put, you need to hit the target and you want to know where the empty cases go so do not wind up with hot cases in someone else’s eyes.

    What happened was simple: In testing various Old School Army Officers discovered they liked the design of the Armalite, but were still hesitant to go with a twenty two gun, and Winchester decided to bid on a contract for the M14 instead of pushing its light rifle.

    The effective incapacitating wound range was in excess of 300 meters, and a small scale test in combat showed the AR-15 and XM193 was more effective than the 7.62x39mm round, and it had a big advantage. The rifle was accurate, and it was light enough to easily be carried in quick response positioning.

    The handling of the AR-10 gave birth to the AR-15 platform and Colt bought the rights to it in 1959. That was in the problem time for the AK, and the SKS was more frequently encountered until 1961. The M16 was a response to the weight and supply issues with the M14, and was not really expected to stay in service that long– something better would be created soon.

    Soon has several definitions.

  13. First, the AR-10 has been in military service since 2004-’05; the commanding general of 2nd Marine Expeditionary Force got it put into production, so if you have an AR-10 that doesn’t come from the original production runs off the 1950’s, you have him to thank!
    Since then, it has been adopted by militaries worldwide, most often as a picked marksman’s rifle (British, U.S.), but it is also adopted as the general service rifle of a few countries, example Turkey. (Speaking of, if you bought an HK 417, that’s a Turkish-built AR-10 service rifle you own.)

    On 5.56 effectiveness at range, this differs widely according to load, purpose, and rifle (or pistol, or SBR). For example, the M193 has minimal lethality at less than 100 yards because it is moving so fast it shoots through with minimal damage; from one hundred to three hundred yards it can be devastating as it tumbles soon after impact; beyond three hundred yards it becomes less lethal, as it loses enough velocity that, again, it starts shooting through with minimal destabilization. All of that applies to the 1:12 twist rifling; 1:7 overstabilizes the 55-grain FMJ, resulting in exceptional drill-like penetration. This data is the result of hundreds of surgeries and autopsies performed by U.S. military surgeons.

    The M855 is the result of NATO adoption of the SS109 standard, requiring 1:7 twist with the specifically intended purpose of increasing wounding and reducing lethality of the 5.56×45 mm cartridge when it was adopted by NATO. Some folks at the U.S. Army thought further reducing lethality of the .22 was a bad thing; the development of the M882 (?) 9x19mm service round by Speer turned up interesting results, and these were applied to the U.S. version of the SS109 specification to greatly improved lethality of the 5.56 throughout its effective range. (Keep in mind that since the turn of the 1900’s, the U.S. standard for point-target effective range of any specific military small arm is the ability to place five consecutive bullets within a six-inch circle.)

    Deer and varminting with the .223 Remington is a very different proposition. In both cases, effective range is limited to the individual shooter and his weapon being able to hit a two-inch target area every time, to prevent wounding. By the way, deer and varminting rounds are widely used by law enforcement and even military for their lethality against human targets under specific circumstances that call for minimizing risk of over-penetration causing civilian non-combatant casualties.

  14. I’d go with the AK47 vs the AR15 and the FN FAL vs the M14.
    Both the AK47 and the FN FAL are more reliable firearms.
    Too bad the US military chose the wrong firearms;ditto the Beretta M9 vs the Glock 17.
    Further if the military had stayed with a 1:14 twist and not used recycled world war one cannon power[the lime buffer loused up the M16]more of our people would have survived Vietnam.

  15. I would agree with most of this except I have a 5.56 I use exclusively for game. Up to and including White Tail and Feral Hogs.

    However, when using 5.56 for White Tail or Hogs, one MUST pay attention to all the key factors. The load must be right, shot placement is critical, a real “tack driver” is a must for ranges out beyond 200 yards. My most recent tack driver happens to be a Rock River R3 Competition rifle to which I’ve added a SWFA scope. Best coyote gun I’ve had in years! And it’s more than capable of taking feral hogs (brain shots only unless you like tracking them) or white tail deer at 200+ yards.

    I find that people who are interested in trophy’s tend to make shots that let the animal run a few yards, I don’t hunt trophies or waste meat with overkill ammunition. I only shoot head shots myself.

    I do also own several AR-10’s in the .308 caliber and another one in 6.5. These rifles are overkill for white tail, even if you make only head shots. I’ve never had a white tail do more than a single step with my .5.56 in the 30+ years I’ve hunted them with that caliber. Coyotes drop immediately and hogs inside of 300 are no match. Even a bad shot brings them down within a short distance.

    Knowing what rounds you’re using and where to hit the game should dictate weather you can ethically take the shot. I’m happy to say with the availability of decent hunting rounds these days (thank you Hornady) the caliber isn’t near as important as it once was with these two calibers. If you can only afford one of the two, go with the .308/7.62×51 NATO AR-10. You can run smaller loads for smaller game but with the AR-15 you won’t be stopping any bears before they get a chance to cause harm (assuming your using the 10 round magazine).

    Ken P.
    USN Veteran (Expert Rifleman)

  16. I have one of each and could only agree with you. The 15 is a varmint / home defense piece with the 10 being a hunting rifle.

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