Feeding the Modern Semi-Automatic Rifle
Top-of-the-line AR magazines.
By Christopher R. Bartocci
Magazines are one of the most important elements of any firearm design. They are responsible for the feeding portion of the cycle of operation. Even in the most proven arm that reliably extracts and ejects, the magazine has to be 100-percent reliable for it to consistently feed properly. Colt offered the semi-automatic-only SP1 AR-15 for commercial sale in 1963, the same year the U.S. Army adopted the selective-fire M16. Since that time, a variety of magazines have been made for AR-type rifles, and some are better than others. Due to the sheer number of manufacturers and variations, it is impossible to cover them all completely in these few pages, but here is a review of some of the best available today, including the specific characteristics and features that make them stand out.
Standard G.I. Aluminum Magazines
The mainstay since the introduction of the AR-15/M16 has been the aluminum magazine. Originally, the 20-round-capacity—later increased to 30-round capacity—aluminum magazine was intended to be carried pre-loaded and discarded after use. They were even listed in the military supply chain as disposable, but in reality the magazines were used repeatedly. Problems resulted because the lightweight aluminum was easily damaged from dropping or rough handling and, since they were designed to be kept loaded for limited periods of time, the top cartridge pushed on the magazine lips and eventually spread them apart, causing malfunctions.
There have been two iterations of followers for 30-round magazines: the original black follower, and the later green follower, which originated as a Marine Corps design. The latter was part of a reliability enhancement program for the M16A2. Because of the cyclic rate of the M16, it was possible for the bolt to push the cartridge into the front of the magazine. This, subsequently, could push the bullet into the cartridge case. To remedy this, the green follower featured extended legs at the front to keep it aligned with the magazine body. All G.I. magazines now feature this improvement.
According to some recent U.S. military reports, the most reliable aluminum magazines are Colt/Okay Industries magazines. Okay Industries of New Britain, Conn., has manufactured magazines for Colt since the 1970s. Okay has the capacity to produce more than 140,000 magazines per month, according its last completed government contract. A recent report indicated some other G.I. contractor magazines were failing to meet military specifications and were causing malfunctions because of out-of-specification dimensions and processes. During the early part of the Global War on Terror, the Army stopped shipments into theatres of war all manufacturers’ magazines other than Colt/Okay Industries. Colt/Okay units are identifiable by Okay Industries’ cage code “33710,” which is marked on the lower left side of the magazine body along with the month and year of manufacture. The floorplates are marked either “Colt” or “Okay.” Through the years I have had extensive experience with these magazines and have never had any issues with reliability, so long as they were not abused or left loaded for long periods.
Aluminum magazines may be on their way out of the U.S. military. There has been a requirement to replace them with polymer magazines, and Picatinny Arsenal in New Jersey is working on its own design as well as testing several commercial, off-the-shelf (COTS) magazines. The original 20-round straight magazines are still in production, but these are mainly used by shooters who have difficulty with the longer 30-round magazines when firing rifles from the bench. Additionally, 20-round magazines are well-liked by Special Operations troops with their Mk12 Special Purpose Rifles, as they enable lower prone-position shooting.
Heckler & Koch High-Reliability Magazine
The H&K High-Reliability magazine stemmed from the German company’s attempt to fix the horrendous deficiencies in the British SA80 (L85A1) rifle program—particularly with English-manufactured magazines. The design was carried over to both government and law enforcement sales as an improved magazine for the AR-15 platform and was later used by H&K with its HK416 family of rifles.
The High-Reliability magazine body is made of steel rather than aluminum and is coated with a special maritime finish to keep it from rusting. The coating also has self-lubricating properties in the inside of the magazine to aid feeding. The feed lips have the same strengthened design as the standard G.I. 30-round magazine. The profile of the magazine is somewhat different from a standard U.S. G.I. magazine with two bends. The H&K magazine features a constant curve that allows the cartridges to follow a natural path, increasing reliable feeding of the magazine. The steel follower is 100-percent anti-tilt inside the magazine body.
A rubber plug was inserted underneath the magazine behind the floorplate. Its purpose was to prevent unintentional release of the floorplate when firing the M203 grenade launcher without any rounds in the magazine. As one comes to expect with German engineering, these are the most expensive and, by far, the heaviest of the 30-round magazines in this lineup.
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