DPMS Panther Arms AP4 Panther Carbine
By Christopher Bartocci

In the 1950s, the ArmaLite Division of Fairchild Engine and Aircraft touted their new revolutionary AR-10 as “Tomorrow’s Rifle Today.” How right they were. But the day of the AR-10 would have to wait nearly 40 years to just show how true that claim was.

With the adoption of the smaller caliber AR-15, which was destined to become the 5.56x45mm M16 rifle, the AR-10 wound up in the scrap heap of the Ordnance Corps, even though it may have well been superior to the home grown M14 which was adopted by the U.S. military. The M-14 had an active service life of only 6 years before the AR-15/M16 would officially replace it as the main battle rifle for the United States military. Though the AR-10 was produced in limited number by Artillerie-Inrichtingen Hembrug-Zaandam of the Netherlands, it would disappear and become one of those extremely valuable collector items of the lineage to the longest serving small arm in U.S. history, the M16.

It was not until the early 1990s when the AR-10 would be re-introduced by its designer, Eugene Stoner. The AR-10 was always special to Stoner. His original design interest was in 7.62mm military rifles and it was noticed by individuals from Ordnance Corps that the AR-10 was unusually accurate for an auto-loading firearm. This was for good reason. Stoner teamed up with C. Reed Knight, Jr. of Knight’s Armament Company and introduced the SR (Stoner Rifle) -25 (10 + 15). This was a match grade sniper rifle based on the AR-10 with many of the advancements of the M16A2 and boasted 60% parts commonality. But it was expensive and scarce to anyone other than military. The development of the SR-25 was paid for through commercial sales. Knight did introduce a very small limited run of SR-25 carbines just before the September 1994 Assault Weapon Ban. These utilized the telescopic carbine stock and a 16-inch free-floated barrel.

In the mid 1990s, Mark Westrom, President of Eagle Arms, bought the trademark along with all other remaining rights pertaining to ArmaLite and reintroduced his Company as ArmaLite. Westrom made many 5.56mm variations of the M16 rifle but his true crown jewel was the reintroduction of the AR-10. The new AR-10A2 and A4 series were modernized AR10’s. Unlike the SR-25, Westrom was more concerned with making a rifle that was designed to be a 7.62mm rifle than a rifle that shared parts commonality with the existing M16A2. Westrom built a stronger rifle utilizing forged receivers instead of extruded ones and at a much more affordable price. In fact, ArmaLite (Westrom) has sold more AR-10 rifles than all the others combined throughout the history of the AR-10. With the new ArmaLite Company geared toward high quality weapons design and sales at reasonable prices, the AR-10 was back and back for good. Westrom did develop his weapon with surrogate components from the SR-25 and did maintain parts compatibility to tap into the existing SR-25 market.

AR-10 Carbine Development

Although the mid to late 1990s showed a variety of different AR-10/SR25 rifles, the one that was usually missing from Knight’s and ArmaLite’s catalogue was the carbine versions. This was due to the federal assault weapon ban that prohibited the use of telescopic stocks, bayonet lugs, flash suppressors and production of high-capacity magazines for commercial use. ArmaLite got around the magazine ban by his converting the countless surplus pre-ban M14 magazines into the magazines for his AR-10A2/A4 family of weapons. If you were fortunate enough to have an SR-25 you were stuck paying nearly $150 for a 20-round magazine. With there being little law enforcement or military interest in a compact 7.62mm weapons system, it made little sense to invest in the development of something you could not sell; at least, not yet.

On September 14, 2004, the federal assault weapon ban expired. These weapons were now legal in most states and civilians were anxious to get their hands on a 7.62mm M4. ArmaLite was the first to respond with their AR-10A4 carbine. This sported a 16-inch barrel with an M16A2-style muzzle break and a telescopic stock. Selling for around $1,400, ArmaLite could not produce enough. Knight’s also responded and in 2005 put into production a carbine version of their SR-25 called the MK11 Carbine, which is made in very limited numbers and sells for more than $5,000.

The DPMS AP4 Panther Carbine

The latest entry into the AR-10 family of carbines is the AP4 carbine manufactured by DPMS Panther Arms and introduced at the 2005 SHOT Show. Selling for $1,249, the AP4 is an extremely high quality carbine that is light, reliable and accurate. Panther Arms offers an entire line of match grade rifles in this caliber but the carbine comes in two configurations with the only difference being the hand guard. One comes with standard hand guards and the other with a free floating hand guard. All come with two 20-round magazines and the DPMS Panther Arms Back Up Iron Sight, sling and operators manual all in a hard plastic carrying case.

The Upper Receiver

The upper receiver is made from thick-walled, extruded from 6066 T-6 aluminum. The receiver is then hard coat anodized to a flat black finish. The top of the receiver has a flattop Mil-Std 1913 rail. A unique aspect of the upper receiver is that it has a forward assist/shell deflector built into the receiver located directly behind the ejection port. Why does the AP4 carbine have a forward assist when Knight’s and ArmaLite do not? DPMS was merely responding to customer demand. Although the forward assist assembly is quite useless and designed to force a bolt closed, which you should never do, there are customers who demand it because the M16 has it. The original rifle was designed without one for good reason but there has been a perceived psychological need for it, not a mechanical need, one which has kept it on the M16/M4 series weapons since the mid 1960s. The customers desired it so Panther Arms provided this feature on their AP4. The shell defector, like on the 5.56mm rifle, prevents ejected fired cartridge cases from hitting the left handed shooter in the face. The standard ejection port dust cover is used as well.

The 16-inch long barrel is manufactured from 4140 chrome-molly steel and has the “step-down” contour of the barrel of the M4 carbine. The barrel is button rifled with a right hand twist of six lands and grooves with a 1 turn in 10-inch twist. The carbine uses a standard profile M16 front sight assembly with the M16A2/M4 square front sight post and a modified Vortex-type flash suppressor. The carbine utilizes a gas tube for its direct impingement gas system.

The test and evaluation carbine was also equipped with a DPMS designed BUIS (Back Up Iron Sight). This is very much a standard M16A2 style rear sigh adjustable for both windage and elevation with both long and short range apertures and is secured by two tension bolts. However, any BUIS can be attached to the standard Mil-Std 1913 rail.

The Lower Receiver

The lower receiver is milled from a solid billet of 6061-T6 aluminum and hard coat anodized to a flat black finish. The trigger components utilized are standard .155 diameter AR-15 hammer, trigger and disconnector. The selector is the A2-style with co witness on the right side of the receiver so a left handed shooter will know the condition of his rifle. The lower receiver is thicker and sturdier than either the Knight or the ArmaLite rifle.

The telescopic stock utilizes an M4-type polymer stock but has 6 sliding positions instead of Mil-Spec four. The carbine uses a different buffer than the standard carbine and is much shorter in length.

The magazine is one of the most interesting features of the AP4. DPMS chose to go with the Knight’s 20-round magazine, which is an enhanced original AR-10 magazine. It is the most optimal choice for the AR-10 type weapon system and now, with the high capacity magazine manufacturing restrictions lifted, DPMS was free to go with this magazine design. Their magazine retails for $59.95.

The AP4 Bolt Carrier Group

Like the SR-25, DPMS went with the original ArmaLite hard chrome plated bolt carrier. Showing that retro look is “in” and the obsolete chrome plated bolt carrier groups have made a reappearance over the last few years after being discontinued in the mid-1960s for the current manganese phosphate finish. DPMS has reverted back to this finish as well on their entire line of 5.56x45mm rifles. Another interesting departure from previous bolt carriers is that DPMS went with two gas vents instead of three that have always been used since the 1950s. Another difference is the firing pin retaining pin. Knight’s went with a captive firing pin retaining pin to prevent this commonly lost part from disappearing at an inopportune moment while ArmaLite went with the standard cotter-style pin. DPMS went with the machined pin similar to the original pins used by Colt in the early days of Vietnam. They were discontinued by the Army in favor of the cheaper and more durable cotter-type pin. This DPMS firing pin retaining pin is over-engineered and very durable.

Both the ArmaLite and the DPMS AP4 use dual extractor springs to increase extraction strength in the higher pressure carbines. Westrom however, utilizes a rubber “O” ring to further enhance extraction reliability. DPMS stayed with a free-floating firing pin like Knight’s whereas ArmaLite put a firing pin spring on the firing pin to lessen the likelihood of slam fires.


DPMS offers a very high quality and economical option to the 7.62x51mm AR-10 family of carbines. The AP4 can serve several roles that include hunting, target shooting and personal defense. It’s lightweight and compactness will take it where few 7.62x51mm caliber rifles have gone before. With the introduction of these lightweight carbines by Knight’s Armament, ArmaLite and DPMS, the 7.62x51mm cartridge has a package that could be suitable for close quarter battle conditions.

The test and evaluation carbine that was received and tested showed no points of concern in any areas. The AP4 carbine was high quality with excellent fit and finish. During live fire testing the carbine experienced no malfunction utilizing American Eagle .308 Winchester, Winchester Supreme 168-grain Open Tip Match, the authors own reloaded 147-grain full metal jacket as well as an assortment of surplus ammunition. The magazines interchanged and functioned flawlessly in both the SR-25 and the AP4. DPMS offers many configurations and add-ons to make the AP4 do anything a smaller 5.56mm caliber carbine can do and much more. Due to the modularity of the AP4 carbine, by replacing the upper receiver group the rifle can be a carbine, standard rifle or a match rifle. Then again, that is the beauty of any AR-15/M16/M4 based weapon system.

PANTHER LONG RANGE 308 C 16-inch AP4 CARBINE (RFA2-308AP4) Barrel:



This article first appeared in Small Arms Review V10N3 (December 2006)
and was posted online on December 28, 2012


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