For the past few years, the large-receiver AR, commonly referred to as the AR-10, has become a popular rifle among American shooters. One of the reasons for this is simply that a lot of AR-15 owners want a bigger version of their black rifle that fires a full-power cartridge.
Unlike the smaller and more popular AR-15 that was adopted for military service in the 1960s, the large-receiver AR doesn’t have a MIL-SPEC standard.
In my search for good AR-10 magazines, I found that most of the early magazine designs, such as the DPMS, have issues feeding rounds. The original KAC SR25 magazine is very expensive, at $95 to $125 each. Its price and availability are due to variants of the KAC SR25 being made for military contracts, various agencies of the U.S. government and our allies around the world.
For the rest of us, here are my top picks for dependable, wellmade AR-10 magazines.
All the featured magazines were tested using my three large-receiver ARs: an Aero Precision M5 model with a 16-inch barrel with forged receivers; Lancer Systems L30 Heavy Metal model with an 18-inch stainless barrel and billet receivers; and a DPMS GII (Gen 2) Compact Hunter model with a 16-inch barrel. The DPMS uses its new, proprietary GII receivers.
An entire article could be written about this, but in a nutshell, there are two patterns of large-receiver ARs: the Eugene Stoner-designed AR-10 produced only by Armalite, and the SR-25 (Stoner Rifle) developed by Eugene Stoner with Knights Armament Corporation (KAC).
Due largely to increased parts commonality with the AR-15, the SR-25 type took off in popularity and became the design all current manufacturers would base their designs on—most notably in the civilian market, the DPMS LR-series. With no MIL-SPEC standard, many manufacturers have varying degrees of design differences with the SR-25.
The one thing that has seen some semblance of standardization is the magazine. There are a few that use other styles, but most makers use SR-25-compatible magazines. These magazines are generally labeled as being compatible with LR/SR or M110 (the military designation for the KAC sniper/designated marksman rifle) systems. Other mag makers just call them 7.62 or .308 AR mags.
The dilemma for this article is what to call these magazines as a generalized group. “LR/SR-25-compatible magazines” would be the most accurate; however, most shooters know the rifle as the AR-10, not the LR/SR-25. Nevertheless, calling it an AR-10 magazine isn’t technically correct and could lead to confusion when purchasing magazines. The reason is that commercial magazines aren’t marked as such, except for those made specific to the Armalite.
Just to clarify and to avoid confusion, this article refers to the large-receiver AR as an “AR-10,” because that’s what most shooters know it as, but we’re referring to magazines for the LR/SR-25 pattern rifle.
Just know that when purchasing magazines, unless you own the actual Armalight AR-10 pattern rifle, most magazines will be compatible with your rifle. Be sure to read the packaging to confirm.
By Robb Manning
MAGPUL PMAG LR/SR
Weight: 7.2 ounces (25-round version)
Capacity: 10-, 20-, 25-round
Colors: black and FDE
MSRP: $19 (10-round); $20 (20-round); $23 (25-round)
I’m comfortable saying that Magpul is instrumental to why the industry adopted the KAC SR25 magazine pattern for the current crop of magazines. Magpul was also the first good polymer magazine for the platform. Named the PMAG LR/SR (but also referred to on Magpul’s website as SR25/ M110), it’s available in the standard 20-round capacity, low-profile 10-rounder and the 25-round extended capacity with additional curve to allow reliable feed of the M118LR and other match-grade 7.62x51mm/.308 Win. rounds with longer projectile.
Much like Magpul’s popular AR-15 PMAGs, the LR/SR is constructed entirely from polymer, with the exception of the stainless steel follower spring. It is very affordable, with a street price of around $20. However, there are concerns about the longevity of the polymer feed lips (especially in subzero temperatures), as well as reports of pitting on the inside front surface from bullet tips after being in use for a while. The Magpul PMAG SR/LR functioned flawlessly in all three of my testing ARs.
Weight: 8.1 ounces
Color: black only
The LaRue Tactical magazine was originally developed for their OBR (Optimized Battle Rifle) large-receiver AR. Its development was started years before the Magpul PMAG LR/SR, and it has gone through a number of revisions since. The LaRue’s magazine body is made from a single sheet of stainless steel and is laser welded at the back. This feature frees up more clearance at the front for the M118LR and other types of ammo with a lengthy bullet.
The inside and outside of the LaRue magazine body are coated with a special finish that’s corrosion-resistant and self-lubricating. The base plate is CNC-machined billet aluminum alloy. It’s secured by a short torx-head bolt in the front, with two small, metal guide pins at the back to keep it centered. The only nonmetal part is the red-colored anti-tilt magazine follower that’s made from glass-reinforced polymer.
Overall, I consider the LaRue LT762 to be the finest metal magazine for the SR/LR-pattern AR. While it’s not cheap ($79 per magazine), it costs 50 percent less than the original KAC SR-25 magazine, weighs less and has a more robust floor plate. The LaRue LT762 magazine worked great with my Lancer and Aero Precision ARs but had a few random feeding issues in the DPMS rifle. This is probably due to its shortened, proprietary DPMS GII receiver design.
It seems odd that when Heckler & Koch (HK) came out with its HK417—an essentially piston-driven AR-10—it chose not to use the SR25 pattern magazine with it. Instead, HK elected to use its own magazine design that was developed from the polymer magazine of its smaller HK416. This, itself, was based on the proven G36 magazine that has been in service with the German military since the early 1990s.
While it’s not compatible with other large-receiver AR variants, the HK417 polymer magazine fixed two main issues with the SR25 pattern magazine: the feed geometry and magwell size limitation. For the first of those, a former KAC engineer told me that Eugene Stoner knew about the original AR-10 magazine having a bad feeding geometry. When the cartridge is pushed out by the forward moving bolt, it first dives down before it comes back up again.
When Stoner was developing what became known as the SR-25 for KAC, he wanted to create a new magazine for it. However, Reed Knight overruled him, because it was cheaper to just use the existing original AR-10 magazine—but with modifications to the mag-catch cut and the feed lips. That set the pattern for all the modern large-receiver AR magazines; and, because of that, they all carry the same feeding geometry defect with various degrees of remediation and improvements. That’s why HK eliminated that problem completely by using a new magazine design that has a straight feeding geometry.
The other advantage of not using the SR25 magazine pattern is that it allows HK to have a better magwell design on the receiver. Because of this, the HK417 polymer magazine features thicker side walls, reinforcement ribs and an embedded stainless steel support at the front to prevent bullet tip pitting.
So, how would HK challenge the SR25 magazine pattern in the near future? Well, recently, the U.S. Army announced it would be adopting a variant of the HK417 as the M110A1 CSASS (Compact Semi-Automatic Sniper System) to replace its existing KAC SR-25-based M110 SASS.
The U.S. Marine Corps would certainty follow this, because it is also a user of the M110 SASS. Additionally, it already had another HK weapon in service—the smaller HK416-based M27 Infantry Automatic Rifle in 5.56mm.
Once gun makers see the advantage of the HK magazine (and the military adoption would help influence this, too), there’s a good chance we might start seeing other makers use the HK417 magazine.
LANCER L7 AWM
Weight: 6.9 ounces (20-round)
Capacity: 20-, 25-, 10-, 5-round
Colors: Clear, Smoke, translucent FDE, black, FDE
MSRP: $50 (20-round); $55 (25-round); $45 (10-round), $55 (5-round)
Lancer Systems had been making composite components for the defense and aerospace industries long before it started making magazines. Much of that expertise had been carried over in the making of its Advanced Warfighter Magazine (AWM) for the AR-15 and AR-10. The Lancer magazine has the advantages of both polymer and metal designs by incorporating an impact-resistant, lightweight polymer magazine body with durable metal feed lips. Lancer’s newer and bigger L7 AWM for the AR-10 is not just a simple scale-up of the L5 AWM model for AR-15; instead, it’s completely re-engineered with several additional features.
The L7 AWM not only has metal feed-lips, the magazine catch hole is now also supported by metal. The top portion of the Lancer magazine is essentially all stainless steel construction, with both the inside and outside pieces laser-welded together. The internal stainless steel piece extends halfway down at the front to prevent pitting from recoil by the bullet tip, and it gives more clearance for longer projectile length. Its reinforced floor plate is thicker, and it has a switchable drainhole feature with a built-in removable plug.
There were no issues using the Lancer L7 AWM with any of my three ARs—even the finicky DPMS GII. It’s a bit over-engineered, with its sophisticated, hybrid metal-and-polymer construction, but the Lancer L7 AWM is the best polymer magazine currently available. It has a lot of capacity and many color options.
D&H TACTICAL SR-25 MAGAZINE
Weight: 8.9 ounces (20-round with witness holes)
Capacity: 20-, 10-, 5-round
MSRP: $25 (20-round)
Known for its affordable USGI magazine for the AR-15, D&H has been in the magazine business for more than 30 years. Its SR-25 pattern magazines are available in two versions: The tactical version features witness holes, crossed support ribs and a red follower. The newer Retro version, which is a direct reproduction of the original SR-25 magazine, features no witness holes, all-vertical ribs and a bright-green follower. Both types have a Teflon-coated carbon steel body. The SR-25 magazine is available in both the shorter, 10-round version and a five-round hunting version that uses a restrictor floor plate. D&H also offers limited runs of the Retro SR-25 model in an aluminum body. However, I would recommend sticking with the steel-body D&H models.
Constructed in the same traditional method as the USGI magazine, the D&H lacks the reinforced floor plate, stainless steel body or the laser welding of the LaRue. However, it’s very affordable for a steel magazine—at nearly the same price point as the polymer magazines. Because it is a metal magazine, the D&H has the advantages of durable feed lips, and bullet tip pitting will not be an issue. The D&H magazine worked just as well as the more expensive magazines in my testing AR-10s, other than a few random hiccups on the DPMS GII. Again, the issue is probably from that gun’s shortened proprietary receiver.
Unlike the smaller and more popular AR-15 that was adopted for military service in the 1960s, the large-receiver AR doesn’t have a Mil-Spec standard.
The SR-25 (and later, the DPMS) is developed from the original AR-10. As for the later AR-15, the magazine of the original AR-10 is lightly built from aluminum and is supposed to be disposable. It’s often called a “waffle” magazine because of the rib pattern on its aluminum body. Unlike modern AR magazines, the waffle magazine uses a metal follower.
Although the waffle magazine would fit into a modern AR-10, it wouldn’t work. Its magazine catch hole, the follower bolt hold-open slot and the feed lips are all different and will not work on modern AR-10s without some modifications.
Editor’s Note: A version of this article first appeared in the April 2018 print issue of Gun World Magazine.