AR-10 vs. AR-15: What Parts Are The Same?

The AR-15 and AR-10 are two of the most popular rifles in America. They're often mistaken for one another. This is no surprise -- both rifles function identically, and they even share some parts. But the AR-10 is quite different from the AR-15. We're comparing them side by side, clearing up the differences and similarities between these two rifles, and breaking down parts compatibility.

What is The AR-10?

The AR-10, designed by Eugene Stoner and introduced in 1956 by ArmaLite, is the first ever AR-type rifle. Chambered in .308, the ArmaLite AR-10 was submitted as a competitor in the U.S. Army's rifle trials -- a competition intended to find a replacement battle rifle for the aging M1 Garand.

The ArmaLite AR-10 is still manufactured today, though its primarily offered to military clients. Few rifles are seen for sale on the civilian market today. Instead, it's the LR-308, made by DPMS Panther Arms, that fulfills demand for the AR-10 platform.

Although identical in form and function, slight differences in how individual components are shaped are what distinguish the DPMS rifle from the ArmaLite rifle. Despite this, the DPMS LR-308 is considered by many to be (and is usually referred to as) an AR-10.

Learn the differences between the AR-10 and LR-308 here.

What is The AR-15?

In response to the U.S Army's request for a lightweight .22-caliber service rifle, Eugene Stoner and engineers at ArmaLite scaled down the AR-10, chambering it in .223 Remington. The resulting rifle was the ArmaLite AR-15. 

The AR-15 is noticeably shorter than the AR-10, thanks to its shorter barrel and more compact receivers. Its smaller cartridge provides a higher magazine capacity, too. The typical AR-10 magazine holds 10 rounds, while the standard AR-15 magazine holds 30 rounds.

ArmaLite sold the AR-10 and AR-15 trademarks to Colt in 1959. Today, Colt still makes the AR-15 as a semiautomatic rifle, as do dozens of other manufacturers. Today, the AR-15 remains the most popular rifle sold in America, with tens of millions of models in circulation.

AR-10 vs. AR-15: What's Different?

Caliber, size and purpose are the three differentiators separating these rifles. The AR-10 is a battle rifle that chambers an intermediate cartridge (.308 Winchester and 7.62x51 NATO), and is intended for engaging targets at medium to long distances. 

The typical AR-10 measures 42" long, but longer match barrels and fixed stocks can increase the rifle's overall length to nearly 50". The average AR-10 weighs between 7.5 and 8.5 pounds loaded, though these rifles are also frequently fitted with high-magnification optics that can bring the total weight up to 9 to 9.5 pounds.

The 5.56 NATO- and .223 Remington-chambered AR-15 is built engage targets at short to medium distances while affording high maneuverability. Intended to be a lightweight and compact rifle, it offers a typical overall length of just 33" when equipped with a standard 16" barrel. It also manages to shed some weight over its larger companion and weighs, on average, 6.5 to 7.5 pounds loaded -- a weight savings of up to 30%.

AR-10 vs. AR-15: What's The Same?

The AR-10 and AR-15 use identical gas systems to operate. Both rifles use the same type of rotating bolt and a direct-impingement, gas-driven bolt carrier group to provide semiautomatic fire. Both rifles use a gas block attached to the barrel to capture and redirect gas into the bolt carrier group via a gas tube.

Both rifles' lower receiver assemblies also function identically. Both use the same type of buffer and recoil spring to reciprocate the bolt carrier group. Both rifles' fire control components -- the hammer, trigger, safety, disconnector, sear, and pins and springs -- all function in the same manner, too.

But, importantly, the dimensional differences between the two rifles mean that not all parts are interchangeable. Some of the AR-15's parts are too small to fit the AR-10 receivers, and the inverse holds true for the AR-10: Some of its parts are too big to fit the AR-15 platform.

See our compatibility charts below to see which AR-15 and AR-10 parts are interchangeable.

AR-10 vs. AR-15 Parts Compatibility

See our compatibility charts below to see which AR-15 and AR-10 parts are interchangeable.

Upper Receiver Components

Component	Interchangeable?
Barrel	No
Barrel nut	No
Bolt	No
Bolt Carrier	No
Charging Handle	No
Detachable Front Sight	Yes
Detachable Rear Sight	Yes
Forward Assist	Yes
Dust Cover	No
Gas Block	Yes
Gas Tube	Yes
Gas Tube Roll Pin	Yes
Handguard	No
Muzzle Device	No
Muzzle Device Crush Washer	No
Stripped Upper Receiver	No

Lower Receiver Components

Component	Interchangeable?
Bolt Catch	No
Bolt Catch Plunger	Yes
Bolt Catch Spring	Yes
Bolt Catch Roll Pin	No
Buffer	No
Buffer Retainer	No
Buffer Retainer Spring	No
Buffer Tube	Yes
Buttstock	Yes
Castle Nut	Yes
Disconnector	Yes
Disconnector Spring	Yes
Hammer	Yes
Hammer Pin	Yes
Hammer Spring	Yes
Latch Plate	Yes
Magazine Catch	Yes
Magazine Release Button	Yes
Magazine Release Spring	Yes
Pistol Grip	Yes
Pistol Grip Screw	Yes
Pistol Grip Washer	Yes
Pivot Pin	No
Pivot Pin Detent	Yes
Pivot Pin Spring	Yes
Safety Selector Lever	Yes
Safety Lever Detent	Yes
Safety Lever Spring	Yes
Takedown Pin	No
Takedown Pin Detent	Yes
Takedown Pin Spring	Yes
Trigger	Yes
Trigger Guard	Yes
Trigger Pin	Yes
Trigger Spring	Yes

AR-15 vs. AR-10 Calibers

The AR-15 and AR-10 platforms accept dozens of calibers. Some cartridges are small enough to fit inside the AR-15's shorter receivers, while others require the long action of the AR-10. These are the most popular calibers that fit in either the AR-15 and AR-10:

AR-15 Calibers

• 5.56 NATO
• .223 Remington
• .223 Valkyrie
• 300 Blackout
• .458 SOCOM
• 6mm ARC
• 6.5 Grendel
• 6.8 SPC

AR-10 Calibers

• .243 Winchester
• .260 Remington
• .300 Win Mag
• 7.62x51 NATO
• .308 Winchester
• .338 Federal
• 6.5 Creedmoor

Ready to Build an AR-15 or AR-10?

No matter which rifle platform you're building, the assembly process is identical for both the upper and lower receivers. Use our helpful step-by-step guides below to assemble your custom AR-15 or AR-10!

• How to Assemble The AR Lower
• How to Assemble The AR Upper