Can I Use An AR15 Rifle Length Buffer In My AR10

AR15 Rifle Buffer vs AR10 Buffer www.308AR.com

AR15 Rifle Buffer vs AR10 Buffer

Can I Use An AR15 Rifle Length Buffer In My AR10 or 308AR Rifle Stock? That is a question we see pretty regularly on the forum and Facebook. The answer is of course no and the reason is simple. The AR-10 and 308AR Bolt Carrier Group are much longer than an AR15 Bolt Carrier Group. Using the AR15 rifle length buffer would not allow the AR-10 and 308AR to cycle completely.

So now your thinking how can a substantially more powerful cartridge use a shorter buffer? That too easy an easy answer or two. A Rifle Length AR-10 308AR buffer will weigh substantially more than an AR15 Rifle Length Buffer.The AR-10 and 308AR Buffer Recoil Spring will also be stronger offering more resistance. Slash of  Heavy Buffers.com does a great job of sorting it out.

Update; Pat Raley our resident AR-10 expert offers up a more thorough and detailed explanation.

The buffers and buffer springs between the AR-10 / .308 style rifles and the M-15 series of rifles are different.  Not just length, but weight also. They are both close in size but yet different enough where they should not be interchanged. Now as for receiver extension tubes… (this is mostly for ArmaLite rigles) There are 3, I say again… 3… I spell t h r e e different size receiver extension tubes. The rifle length is the same for the AR-10, as it is for the M-15. The carbine receiver extension tubes are different. The AR-10 is longer to allow the larger bcg to make the distance. In theory. .. you can not use an M-15 receiver extention on a AR-10. 
(Another story at a different yime)

 

 

Carbine…..we will save that fo another post at a later date.

Armalite AR10 Buffer Dimensions

Armalite AR10 Buffer Dimensions- Armalite AR10 Carbine Stock Kit

Armalite AR10 Carbine Stock Kit

Armalite AR10 Buffer Dimensions – To understand the differences between the Armalite AR-10, AR15 (M-15) and 308AR platforms is to have a good understanding of the dimensions involved in the buffer recoil system. The system includes the receiver extension tube or buffer tube, buffer and buffer spring. This page is strictly devoted to the Armalite branded weapons the Armalite AR-10 and Armalite M-15. This information does not apply to DPMS LR-308 and other 308AR firearms.

 

Armalite AR-10 Carbine

Armalite AR-10 Carbine Buffer Dimensions3 1/4″ Part Number EC0120

Armalite AR-10 Carbine Buffer Tube Dimensions – 7-5/8″ Part Number 10207025

Armalite AR-10 Carbine Spring DimensionsMax 11-1/4″ Min 10-1/6″ Part Number EC0040

 

Armalite M-15 Carbine

Armalite M-15 Carbine Buffer Dimensions3 1/8″ Part Number EC0030R

Armalite M-15 Carbine Buffer Tube Dimensions – 6-15/16″ Part Number 15207020

Armalite M-15 Carbine Spring DimensionsMax 11-1/4″ Min 10-1/6″ Part Number EC0040

 

Armalite AR10 Buffer Dimensions - Armalite M15 A2 Rifle Stock Kit

Armalite M15 A2 Rifle Stock Kit

 Armalite AR-10 Rifle

Armalite AR10 Rifle Buffer Dimensions5.2″ Part Number EA1090

Armalite AR-10 Rifle Buffer Tube Dimensions – 9-11/16″ Part Number  EL0370

Armalite AR-10 Rifle Buffer Spring Dimensions14-1/8″ Part Number EA1095

 

Armalite M-15 Rifle

Armalite M-15 Rifle Buffer Dimensions5 7/8″ Part Number EL0180

Armalite M-15 Rifle Buffer Tube Dimensions – 9-11/16″ Part Number EL0370

Armalite M-15 Rifle Buffer Spring Dimensions – Max 13-1/2″ Min 11-3/4″ Part Number EL0210

Armalite AR10 Buffer Dimensions


AR15 PMAG Vs 308 AR LR20 PMAG

AR15 PMAG Vs 308 AR LR20 PMAG
AR15 PMAG Vs 308 AR LR20 PMAG

One of the subjects that often confuses shooters about the AR15 and 308AR is the size differences in the platform. We often hear “Can I shoot .308 in my AR15?” and the answer of course is no. I think one of the easiest way to illustrate the reason why is with AR15 PMAG Vs 308 AR LR20 PMAG size comparison. In the picture above it’s easy to see that the larger .308 Winchester cartridge requires a larger receiver, chamber and of course a larger magazine. A 308AR magazine cannot fit into the magazine will of an AR15.

View our 308AR compatibility page for further information.

AR15 PMAG Vs 308 AR LR20 PMAG


DPMS 308AR Receiver Height Comparison

DPMS 308AR Receiver Height Comparison

DPMS 308AR Receiver Height Comparison

DPMS 308AR Receiver Height Comparison – The fine folks at Troy Industries created a document displaying the different receiver heights of DMPS LR 308 308AR receivers. Support this site by viewing Troy Industries products here and here.

DPMS LR 308 308AR Receiver Height Comparison

DPMS 308AR Receiver Height Comparison

DPMS 308AR Receiver Height Comparison

DPMS 308AR Receiver Height Comparison


Armalite AR-10 The Only AR-10

 

Armalite AR10 A4 10A4CF

Armalite AR10 A4 10A4CF

 

In late 2007 308ar.com was born out of several thoughts and ideas. The first being that AR15 shooters would eventually seek a more powerful platform, hunters not interested in a 5.56 weapon might embrace the more powerful 7.62/.308 Winchester cartridge and long range precision target shooters would gravitate towards and appreciate the modularity of the 308AR platform. Lastly that while on the surface the Armalite AR-10, DPMS LR-308, and AR15 look similar there are substantial differences. The AR15 difference should be obvious as a 7.62 rifle, .308Winchester cartridge is longer longer than a .223/5.56 and simply cannot dimensionally fit in a mil-spec AR15. This leaves us with the subject of this post, the Armalite AR-10.

First off let’s start with the simplest reason all 308AR rifles are not an AR-10. The Armalite “AR-10” is a trademarked model of rifle from Armalite. To call all 308AR rifles AR-10 is like saying every cola is Coke, every muscle car is a Mustang or all plastic wrap is Saran Wrap. All three of those products are trademarked names of their respective brands and should not be used interchangeably.

Now for the more complex reasons the Armalite AR-10 is the only AR-10. In 2015 the differences are now less then the were three years ago but they are no less confusing and no less insignificant.

DPMS LR-308 Lower Receiver with an Armalite AR-10 Upper Receiver

DPMS LR-308 Lower Receiver with an Armalite AR-10 Upper Receiver

Armalite AR-10 Upper Receiver – the Armalite AR-10 upper receiver has a profile that prevents it from properly fitting on a DPMS LR-308 style profile. An Armalite AR-10 upper receiver should only be used with an Armalite AR-10 lower receiver. The Armalite AR-10 upper receiver uses a barrel extension and bolt unique to the Armalite AR-10 upper receiver. Do not use a DPMS LR-308 bolt in an Armalite AR-10 barrel/barrel extension. Likewise do not use the Armalite AR-10 bolt in a DPMS LR-308 barrel/barrel extension.

Armalite AR-10 Upper Receiver Compared to a DPMS LR-308 Upper Receiver

Armalite AR-10 Upper Receiver Compared to a DPMS LR-308 Upper Receiver

Armalite AR-10 Lower Receiver – the Armalite AR-10 Lower Receiver has a unique profile and should only be used with an Armalite AR-10 Upper Receiver. There are two Armalite AR-10 Lower Receiver styles prevalent today. The most common uses the proprietary Armalite AR-10 magazine once based on the M14 magazine which was developed and utilized as a result of the Clinton era Assault Weapon ban. These Armalite AR-10 Lower Receivers are not compatible with DPMS-LR 308 magazines, Magpul 308 AR magazines or Knights Armament SR25 magazines or their clones.
Recently Armalite resurrected their preban Armalite AR-10 lower receiver which will accept  the DPMS-LR 308 magazines, Magpul 308 AR magazines or Knights Armament SR25 magazines and their clones.

Lastly in 2015 the lines of compatibility are blurring even further. So many companies producing the 7.62/.308 Winchester based weapons and nearly all following the DPMS LR-308 basic design yet that does not guarantee 100% compatibility with other 308AR weapons. With no mil-spec design we are seeing a lot of creative liberties with weapon designs. It’s a blessing and a curse. Know what your buying. If unsure of compatibility contact the manufacturer or join the forum and tap the knowledge base of the community

 

Read more information here.

 

Armalite AR-10 The Only AR-10


Compatibility

LR-308 AR10 AR15 Platform Cross Compatibility:


308 AR Parts Compatibility

The large platform AR rifles are a great source of confusion and mystery for folks looking to get into the .308 AR world. The number one question being are the parts from a standard AR15 compatible with the Armalite AR10 and DPMS LR-308? Well if only it was a simple yes or no question. The fact of the matter is the LR-308 and AR10 aren’t even completely interchangeable. Hopefully in the paragraphs that follow we can sort all of this out.

Update: As we head in to 2014 there are simply too many brands and variations to list on this page. While i will use it for the most basic of questions I suggest visiting the forum for up to date information.


AR10 vs LR-308 Manufacturers

Before we dive into the compatibility its important that you determine the platform your rifles lower receiver is based upon. Below I will group the big names you will come across when looking for parts. It will by no means be a complete list

Armalite AR10

  • Armalite
  • Eagle Arms
  • Noveske N6
  • Aero Precision
  • Aircraft Armament
  • Iron Ridge Arms (DPMS also)
  • CMMG (DPMS also)

DPMS LR-308

  • Too many to list

.308 AR Pattern Compatibility Frequently Asked Questions

  • Can a Rock River Arms LAR-08 .308 Upper be used with a DPMS LR-308 Lower – No, the upper is longer than a DPMS unit. View image below

    LAR-308 vs LR-308

    LAR-308 vs LR-308

  • Is an Armalite barrel and barrel extension compatible with a DPMS LR-308 Upper Receiver? – Yes, Dimensionally the measurement from the back of the lugs to the breach face is within .001″-.002″ on the Armalite and DPMS bolts. Note: You must use a properly headspaced bolt that matches the barrel extension type. This means you need to use an Armalite Bolt in an Armalite Barrel Extension and likewise for DPMS.
  • Can a Rock River Arms RRA two stage trigger be used with a DPMS LR-308? – Yes, but some times the hammer needs to have some minor filing or stoning to prevent it from dragging on the bolt carrier while cocked.
  • Magpul MIAD pistol grip doesn’t properly hold the rear takedown pin – Magpul addresses this with an adapter called MIAD AR-10/SR-25 Grip Wedge.

LR-308 vs AR10

For the most part I will point out what’s incompatible rather then list every part.

  • Upper Receivers – This is the most significant difference. They are not compatible for the most part. There are cases of folks modifying them to work together but the results are unacceptable and unsightly in my opinion. Click on the images below to view them full size. Images courtesy of AR15Barrels.com
AR10 vs DPMS Upper

AR10 vs DPMS Upper

Armalite AR-10 Upper, DPMS LR-308 Lower

Armalite AR-10 Upper, DPMS LR-308 Lower

 

AR15 vs .308 AR

  • Free Float Tubes and Handguard’s – Most not compatible due to the barrel nut size difference

Can I Mix DPMS and Armalite Upper and Lower Receivers

While you can make it work the contours and profiles are completely different. I’m going to call this a NO


Can I Shoot .308 Winchester Ammunition 7.62×51 Chamber

NO. Note: Others will disagree

The cartridges are slightly dimensionally different and do not headspace the same. The .308 Winchester Cartridge operates at considerably higher pressures than the 7.62.51 NATO. The two should not be used interchangeably. My rule of thumb is to shoot the caliber stamped on the barrel. If you are not sure what your weapon shoots consult the original manufacturer.


Can I Use a .308 AR or AR-10 Upper Receiver on an AR-15

NO, The lower receiver is not large enough to accommodate the .308 Winchester/7.62×51 Cartridge

Can I Use a .308 AR or AR-10 Upper Receiver on an AR-15 Can I Use a .308 AR or AR-10 Upper Receiver on an AR-15


Can a Rock River Arms LAR-08 .308 Upper be used with a DPMS LR-308 Lower

No, the upper is longer than a DPMS unit. See top image