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AR-15, AR-10, 308 Compatible Parts, Eighty Percent Lower Receivers, Interchangeable Parts

Can An AR-15 And An AR-10 Use The Same Parts?

Today We’re Going To Go Over Which Parts Are Compatible Between The AR-15 And The AR-10

Some parts will have to be different and these usually are related to the different calibers of the AR-15 and AR-10. This simplifies things, but it doesn’t paint as clear a picture as going piece by piece.

To make things easier we are going to look at the Upper Receiver parts and Lower Receiver parts as two distinct groups. Additionally, the AR-10 platform is not as standardized as the AR-15. Things like Picatinny, M-Lok, or similar mounting methods are not going to be covered as they are usually universal within their systems.

Complete Upper Receivers

This is where the major variations will be. A complete upper receiver is the combination of all the necessary parts that attach to the base upper receiver. The upper receiver itself can have some variations but we are going to start with the firearms’ muzzle devices.

Muzzle Device

The muzzle devices of AR-15s and AR-10s are not compatible. This is because of the different diameters of their projectiles. While a muzzle device designed to be used with .308 or 7.62×51 NATO can be used on an AR-15, a 5.56 muzzle device cannot be used on an AR-10.

It is best to use the correct caliber muzzle device for your gun, otherwise you run the risk of the device and barrel being damaged.


The barrels are not compatible for the same reasons as the muzzle device. A 5.56 barrel cannot accept a .308 projectile, and a 5.56 projectile could damage a .308 barrel. The chamber sizes will be different and the barrel won’t be able to mount to the receiver properly.

Barrel Nut

The barrel nuts are not cross compatible. This is because they usually have different thread pitches. You could force the threads to work, but this would damage the components and defeat the purpose of assembling the firearm.

Ejection Port and Cover

The ejection port and its cover are not compatible. This is because the port needs to be able to eject the full cartridge and the spent shell. Since the dimensions between 5.56 and .308 are different in overall length they will not work with each other.

Upper receiver

The upper receivers are not compatible. This comes from a combination of the different threading, ejection port sizes, and overall dimensions being different since they have to deal with different stress parameters. These parameters are set by the caliber with everything else being designed around it.

Gas System: Tube, Block, and Pins

The gas systems of the AR-15 and the AR-10 are compatible. This includes the gas tube, the gas block, and the gas tube roll pins.

Bolt Carrier Group

Since the AR-15 and AR-10 are using different calibers, their bolt carrier groups will be different. The bolt head or bolt assembly in addition to the bolt carrier are not cross compatible.

Complete Lower Receivers

The complete lower receivers of the AR-15 and AR-10 have more compatibility, but there are still differences related to caliber.

Lower Receiver

The lower receivers on AR-15s and AR-10s are not compatible. This is due to the different requirements for the magazines, especially in size. They also have to match the dimensions of the upper receivers.

Trigger System

AR-15s and AR-10s use the same triggers. While there may be different specialized triggers for each, on the whole, every trigger designed for either gun is compatible

Bolt Catch

The bolt catch is not compatible between the rifles. This is because of the different locking surfaces between AR-15 and AR-10 bolts.

Bolt Catch/Plunger Spring

This part set is problematic. The bolt catch spring and plunger are compatible. But the bolt catch itself is not compatible. The bolt catch roll pin will work with AR-15s but DPMS AR-10s are not compatible, while other AR-10s may be able to use the same roll pins.

Magazine Catch

The magazine catches are not compatible between AR-15s and AR-10s. This is from the different magazine designs between the two rifles.

Magazine Release

The magazine release will work with AR-15s and some AR-10s but will not work with DPMS style AR-10s.

Magazine Release Spring

Magazine release springs are universal in their usage between the rifle platforms.

Pistol grip

The pistol grip with its screw and washer can be freely transferred between these rifle patterns. Since it helps keep the trigger in place and is not directly related to ammunition, this should not be a surprise.

Take-Down Pins

Due to the different dimensions of the AR-15’s and AR-10’s upper and lower receivers, their connecting take-down pins will not be compatible.

Take-down Spring and Detent

These subsets of the take-down pins are compatible. This comes from the simplistic nature of their role, maintaining enough tension for the pins to stay in place.

Safety Selector

The safety selector is another universally compatible part between the AR-15 and AR-10. Any problems encountered here will come down to out of spec parts.

Safety Selector Spring

This is another compatible sub-part related to the trigger group and does not interact with the caliber of the gun directly.

Buffer Tube

The buffer tube, which holds the buffer, spring, and buffer retainer are interchangeable.


The buffer is not compatible between the AR-10 and AR-15.The reason is that the buffer has to be properly weighted to smooth out the recoil and time the gun.

Buffer Retainer and Retainer Spring

These items are compatible on both AR-15s and AR-10s.

Buffer Spring

Due to the different spring weight/strength requirements, AR-15s and AR-10s cannot share buffer springs without compromising the function of the guns.

Receiver End Plate

Since the end plate holds the receiver together, it is a universally compatible part interacting with the receiver and buffer tube in order to secure them together.

Castle Nut

As with most things related to the buffer tube and its connection to the lower receiver, the castle nut is a compatible part between the AR-15 and the AR-10.

Stock Assembly

Since stock assemblies fit over the buffer tube, you can easily swap out the stock assembly on both AR-15s and AR-10s. Even to the point of swapping them between the rifle designs, as long as a standard buffer tube is used.

Final Considerations

There are a lot of cross-compatible parts on AR-15s and AR-10s, however this does not take into account variables in manufacturing. As long as all parts are made in their appropriate specifications, the compatible parts will work between rifles.

However, the AR-10 features less standardization than the AR-15. This makes parts compatibility harder even within the AR-10 series of rifles. Knowing which pattern your AR-10 is will help you select your parts. However this does not apply to parts that might be defective.

If you are experiencing issues with parts that should be compatible, check their specifications to see if they are sized correctly for your rifle and check your AR-10 pattern if it only works with your AR-15.