Unless you’re already deeply familiar with sporting arms, or perhaps have served in the military, if you saw an AR-15 and an AR-10 side by side on a rack at a gun shop, you probably wouldn’t be able to tell them apart.
That’s not a slight - these two platforms are profoundly similar in many ways, and some parts across them are interchangeable. Both are mag-fed rifles, have collapsible stocks, and utilize a gas impingement system paired with a buffer tube system to cycle a bolt carrier group that feeds, extracts, and ejects spent cartridges.
All the same, they are not quite the same, and the two platforms each have their own virtues. Here’s what you should consider before getting an AR 10 upper and lower and starting your build - you might want to go lighter after all.
Basic Differences
The most substantial difference between the AR15 and AR10 is in chambering. The AR15 is chambered in an intermediate cartridge, the 5.56x45mm NATO (roughly equivalent in ballistic performance to .223 Remington) , whereas the AR10 is chambered in 7.62x51mm NATO (similar to but not the same as .308 Winchester).
The AR-10 is also a much, much heavier rifle. Even unloaded, it usually weighs 10 pounds or more and can weigh as much as 18, depending on barrel length, buffer weight, and how it is outfitted. The AR15 is by contrast much lighter, usually tipping the scales (unloaded) at somewhere between 6 and 8 pounds.
Standard mag capacity is also a bit different. It’s 30 for the AR15 and 20 for the AR10, but that’s just a standard and can easily be adjusted with extended mags.
The AR10 is also older and costs more, whether you buy one prefab or build it yourself with an AR 10 upper, lower, and parts kit. It’s a more expensive rifle.
Now, to go back to the first point, which constitutes the real difference between these platforms. The AR10 is a heavier rifle that’s built for shooting disciplines and applications that require a larger, heavier cartridge that delivers more stopping power - so we need to peel back the layers on this.
7.62x51mm NATO vs 5.56x45mm NATO
There is a wide gulf in performance between 7.62 and 5.56, which results in the most substantial differences between the AR10 and AR15 platforms.
Both developed as military cartridges in the 1960s, and still both very popular (as are their civilian counterparts), these cartridges offer very different load data and ballistic performance.
For one, the 7.62 is loaded with a wider, larger, and much heavier bullet. A 123-grain bullet is typical in a 7.62 cartridge whereas a 62-grain (weighing less than half) is more common in the 5.56.
Muzzle velocity and energy are also substantially different. These figures vary according to load data, barrel length, and other factors, but for the 5.56, muzzle velocity and energy are usually in the area of 3,000 FPS and 1,290 ft-lbs, versus 2,300 FPS and 1,580 ft-lbs for the 7.62.
This makes the 7.62 a much heavier, harder hitting round, and one that also retains energy much better downrange. It is important to note, however, that the sectional density of both (used to determine penetrating capability) is very similar.
The 7.62 retains more energy on target at nearly any range when compared to the 5.56, but there is also trajectory to consider. At 300 yards, the 5.56 will drop 8.6” where the 7.62 will drop nearly 15”. It’s even worse at 500 yards, with the 5.56 down 53.5” to nearly 97” for the 7.62.
Another thing to mention here is recoil, although these are both very light recoiling rounds. The 5.56 usually produces about 5 ft-lbs of felt recoil whereas the 7.62 should produce a little more than 8. But, even though the 7.62 produces nearly twice as much as the 5.56, it is still a very low figure and most shooters can shoot these rounds all day with little to no fatigue.
Also, though this doesn’t have to do with performance, keep costs in mind. The 7.62 is a more expensive round, so if cost of ammo is a consideration for you, remember that.
Where the AR-15 Is Better
The AR-15, when chambered in 5.56, produces higher muzzle velocities, less recoil, and a flatter trajectory than the 7.62. It also produces less stopping power, especially at greater ranges, and is more affordable to shoot, by virtue of the low cost of the cartridge.
This makes the AR-15 (in 5.56) a great option for target shooting and competition, especially 3-gun, as it is lighter and easier to carry, and more maneuverable.
It’s also arguably better for long-range shooting if the target is just that - a paper or steel target, because stopping power won’t matter.
Also, it can also make a great defensive rifle because the rifle will hold more rounds and the ammo is lighter and easier to shoot and has a similar sectional density to 7.62.
Where the AR-10 Is Better
The AR-10 is heavier, more expensive, and holds fewer rounds than the AR-15, and the 7.62 is a heavier cartridge that has a trajectory that’s not nearly as flat.
With that said, the AR-10 has two big advantages. It has a greater effective range and retains ballistic energy more effectively downrange, so for hunting large game, it is far superior.
The AR-15 is not generally considered suitable for taking large game, but the 7.62 and .308 can, with effective shot placement, be used to harvest nearly any game animal in North America. So, while the AR-10 is a heavier rifle to carry in the field, it is far better for hunting large game.
It’s All About How You Intend to Use the Rifle
Ultimately, it comes down to what your intended shooting discipline is. Both can make excellent sporting or defensive rifles. It’s just a matter of what you’re looking for in terms of cost, power, and long-range performance.
Beginning a Build with an AR 10 Upper
Ready to get started with your build? Whether you’re looking for AR-15 or AR 10 uppers, lowers, or parts kits, we have them. Check out our collection and get in touch with us at Sales@MCSGearup.com if you have questions.