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ExarKun 07-13-2011 11:33 AM

AR-10/AR-15 difference?

Besides of the different caliber, what are the other technical differences of the AR-10 compared to the AR-15?

I ask this question in this sense:

I would like to mount the Magpul .308 PRS in my HK MR308 (it is called MR762 in the US, I guess).

In a german forum one guy said, that the PRS uses the same buffer tube like the AR-15. But is that possible? Due to the "bigger" caliber of the AR-10, the receiver has to be more massive, therefore the buffer tube must be wider in its diameter and the buffer spring of the AR-15 should be too weak to make the AR-10 receiver slide forward again.

Has anyone already tried to mount an PRS on the MR308 (IF possible)?



mjkeat 07-13-2011 12:45 PM

I am not up on AR10 style rifles but I do know you can use .308 receiver extensions on AR15s. That leads me to make the assumption that you could mount a PRS on an AR10 style AR.

Someone will be along shortly w/ a more concrete answer.

ExarKun 07-13-2011 12:52 PM


Yes, you can usw .308 receiver extensions on the AR-15, because the AR-15 and the AR-10 use both a mil-spec buffer tube.

Thats what I read in an other forum.

And there lies the problem. The buffer tube of my MR223 is 30mm in diameter, so I can Install i.e. the UBR Stock on the MR223.

The MR308 has a 35mm buffer tube and the question is: does the PRS .308 also have a buffer tube in this diameter?

I fear not.

Any different opinion?

neilage66 07-13-2011 01:02 PM

AR15 = scaled down AR10

The only difference in the PRS stock body is the length of the cheek riser.
The riser on the AR10 version is shorter to accommodate the longer charging handle stroke.

There are many variations of buffer and spring to choose from depending on your upper.

dnthmn2004 07-13-2011 01:05 PM

First, stop by the introductions area and tell us a little about yourself :)

Second, I did a little research for ya and found some detailed info..

Here are the two different PRS's, one for AR-15 and one for AR-10.



Not sure if it answers your question, but more or less gives you another problem. :rolleyes:

ExarKun 07-13-2011 01:27 PM

@ neilage66 @dnthmn2004:

Thank you, but I knew all that before. The most important question for me is: does the AR-10 also have a mil-spec buffer tube, or has the AR-10 buffer tube a bigger diameter?

neilage66 07-13-2011 01:35 PM

From ArmaLite faq:


•.223 / .308 rifle length 9-11/16” (inside depth)
•.223 carbine length 6-15/16” (inside depth)
•.308 carbine length 7-5/8” (inside depth)

Commercial size tube O.D. - 1.165” – 1.167” (we don’t use this anymore)
Military (G.I.) size tube O.D. – 1.145” – 1.147” (carbine and rifle)

JonM 07-13-2011 01:39 PM

There is no milspec standard for ar10 as it has never been adopted by any military. Each parts manufacturer pretty much designs their own. So any cross use between different platforms is purely hit or miss. With non-milspec there is often fitting required to make some things work. Even with milspec swapping parts is sometimes an issue altho the ar15/m16 suffers from this less than most.

My opinion:
With ar10 you should treat them as a sole standalone rifle regardless of its cosmetic similarity to the ar15

neilage66 07-13-2011 01:55 PM


Originally Posted by JonM (Post 540228)
There is no milspec standard for ar10 as it has never been adopted by any military.

Your statement does not paint the full picture in regards to the AR10.

The AR10 has been purchased and used (albeit in limited quantities) by the armies of Guatemala, Burma, Italy, Cuba, Sudan, Portugal, Canada and the United States.

Does this mean it was *not adopted*...yes and no. ;)

JonM 07-13-2011 02:13 PM

The remington 700 falls under that as well but there is no milspec standard. When i said adopted i meant as a country's main battle rifle.

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