A High-Tech Solution To A Low-Tech Problem

posted on June 22, 2010

AR rifles have received a lot of attention lately—the understatement of the decade—but while we’ve all been looking at the guns, a clever little company in Arizona has focused on the magazine. TangoDown has developed what the military calls an “advanced reliability combat magazine” and it may well be the most high-tech piece of low-tech equipment ever developed.

Dubbed the ARC magazine (Advanced Reliability Combat), this highly sophisticated device is not at all what it appears—a hollow chunk of plastic with a spring inside.

Aluminum GI mags are stamped aluminum using two halves spot welded together lengthwise. There’s a straight section that fits in the mag well, then a slight curve, then another straight section. Not an optimum shape, as the curve is potentially a place where springs bind and followers snag. The only way to make a smooth path for the follower and spring is with a constant radius curve joining the mandatory straight section that fits inside the mag well.

This presents a manufacturing problem for a plastic or polymer magazine. Certain polymers are superior to aluminum due to impact and corrosion resistance, butit hasbeenimpossible to produce a straight section joined with a constant radius section from an injection mold—the part couldn’t be removed from the mold. Accordingly, all other attempts at polymer-formed magazines have done away with trying to combine a straight section and a curved section, instead making a constant curve all the way.

The trouble here is the old round-peg-in-a-square-hole conundrum. The only way to fit a curved surface inthe straight mag well of an AR is to make the magazine walls as thin as possible, anddepending on mag well tolerances, magazines won’t drop free, especially when dirty or muddy.

TangoDown solved this problem with a patent-pending two-piece design consisting of a straight section to fit the mag well and a constant-radius-curved section to protrude below the mag well. Fortuitously, this design solution allowed them another significant plus—the magazine could be molded out of different materials.

If you think about it, the upper section of a magazine incorporates the feed lips so it needs to be abrasion resistant and exhibit tensile strength for cartridge control. The bottom section is never rubbed by a high-speed bolt, but it’s thumped, bumped, knocked and dropped, so it needs to be impact resistant. The ARC mag is made from a material that’s optimal for heat and strength and another that’s impact resistant. Translucent materials have been selected for the lower half of the magazine, allowing quick visual assessment of ammunition quantity status.

At the same time, TangoDown addressed the environmental requirements of the U.S. military which call for the magazine to withstand a 6-foot drop test from minus 40 degrees Fahrenheit to plus 140 degrees. The ARC mag meets that as well as another requirement to function in every 5.56 magazine-fed firearm in the military’s inventory, which includes the M249 SAW.

Finally, the military doesn’t always shoot live ammo. Blanks are oftenused in training. TangoDown developed a version of the ARC magazine that functions only with blank ammo and cannot accept a live round. This is a huge improvement in safety.

A lot of companies have spit out magazines to fill the voracious demand for AR accessories, but only a little company in Arizona has really engineered a superior new style of magazine.


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