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The Difference Between AR15, DPMS, SR25, and LR .308

What Is the Difference Between AR15, DPMS, SR25, and the LR .308?


Just because things look the same, it doesn’t mean that they are equal. Crackers are always made out of flour and crunchy whereas cookies are usually sweeter, and have additives like fruit or chocolate chips. Just the same, shrimps and prawns might look the same but have a different anatomy. There you are; the same but subtly different. Now look at an AR from the outside and it looks like, well, an AR, but there can be a lot of different things going on inside the packaging. So, they may all look like an AR, but what are the major differences between the AR15, DPMS, SR25, And LR .308 models?


On the face of it, they look much the same, function in exactly the same way and even have a bunch of common parts, but are subtly different. A key notion to this question is the fact that there is no single type of AR chambered in .308. In fact, there are a fair few of them, and each one is just slightly different. Let’s have a look at the three major stand-out versions of the pack.


The AR-10 is owned and manufactured solely by the ArmaLite corporation, and was designed by Eugene Stoner in 1955. Originally developed as a weapon for paratroopers and other military personnel, this is the first AR-platform rifle ever built and is more powerful, being chambered for 7.62×51 ammo. There are two primary differences between the AR-15, which is chambered for 5.56/.223 rounds, and the AR-10 or AR-308: The .308 rifle is physically larger, and it fires a bigger caliber. From there, everything else about the two rifles are mechanically the same, that is to say:

    • Both rifles use direct-impingement gas systems
    • Both rifles use detachable box magazines
    • Both rifles use a buffer and recoil spring
    • Both rifles use the same trigger setup and parts
    • Both rifles use the same Bolt Carrier Group (BCG) design, though the .308 version is larger.

Study the comparison of the two rifles above, and you’ll find they appear to share many of the same parts, too. There are just a few parts that the AR-15 and AR-308 cannot share.



The SR-25 is a more up to date equivalent to the ArmaLite AR-10, and was also developed by Eugene Stoner, though not until the 1990s, when he began working for Knight’s Armament Company. Today, the U.S. Military has adopted the SR-25 as a service-issued Designated Marksman Rifle (known as the DMR for short). After some modifications, The United States Special Operations Command (SOCOM) began to adopt the SR-25 as the Mk 11 Mod 0 in the early 2000’s. Beginning in mid-2011, SOCOM began divesting the Mk 11 Mod 0 from their inventory and replacing it with the SSR Mk 20.

Regarded as a real marksman rifle, The SR-25 enhanced match rifle utilizes the newer URX II Picatinny-Weaver rail system, rather than the older Mk 11 free-floating rail accessory system (RAS), on the top of the receiver. This modification allows the weapon to accept either different scope mounts or a carrying handle with iron sights if it’s not being used as a specialist sniper rifle.

The Mk 11 Mod 0 system was chambered for 7.62×51mm and utilizes an Obermeyer 20-inch match target barrel, along with a RAS (Rail Accessory System) fore-end which allows for quick attachment or detachment of MIL-STD-1913 components. The aluminum fore-end makes no contact with the barrel forward of the receiver, allowing for extreme accuracy. The Mk 11 Mod 0 has an empty weight of 15.3 lb. and an overall length of 45.4 inches. The non-military version of the SR25, fitted with the longer 24-inch match barrel, is guaranteed to produce groupings of less than 1 inch at 100 yards, or 0.3 angular mil, using factory match loads. By comparison, the match version is designed to shoot at a precision of 0.5 minutes of angle, which corresponds to around 0.5-inch groups at 100 yards.


(Defense Procurement Manufacturing Services) Panther Arms have manufactured bespoke AR15’s for both military and civilian markets. They manufacture AR-15-style rifles chambered for the .223 Remington/5.56×45mm NATO, and AR-10-pattern rifles for the .308 Winchester and .260 Remington cartridges, among others. DPMS have been behind several notable peripheral modifications, such as a positive aluminum magazine catch for easy ejection of magazines, and a 6- position collapsible stock to allow the shooter to adjust length of pull to their personal preference, have made DPMS weapon sought after. The lightweight contour 16.1″ 4140 chrome moly steel barrel normally fitted includes an A2 flash eliminator, and the 1:9″ twist rate is fast enough to stabilize heavy bullets like the 69gr match round, and can still accurately fire standard 55gr ball ammo.

LR .308

This is basically a AR10 but is actually another offering from DPMS based on the AR10 rifle. Basically, an AR15 but in .308 guise, the LR.308, some parts are compatible, but there are also a number of notable differences too.

  • Upper Receiver: This is the most significant difference between the two weapons, and are not compatible for the most part. There are cases of serious gun modifiers getting them to work together but the results are usually unacceptable, unsightly, and potentially dangerous. Best not to fiddle.
  • Barrels: While the barrels are the same the barrel extension and the threads of the barrel nut are not the same, so don’t try getting them on.
  • Bolt Carrier Group:  The bolt carriers are interchangeable if used as a complete unit. You cannot interchange the bolts by themselves.
  • Magazines: These really are not compatible. Furthermore, if you have a LR-308 based rifle from a manufacturer other than DPMS you need to be certain which particular magazine type the lower receiver on your rifle accepts.

You are also going to find differences in the Free Float Tubes and Handguard’s – which are not compatible due to the barrel nut size difference.