The text below is directly from SUREFIRE.

As in other wars, enemy ambushes have been common in Afghanistan and Iraq. The hard lessons of experience have taught that the ability to respond with overwhelming firepower within the first thirty seconds of such an attack can be significant in determining the outcome. However, the goal of enabling warfighters equipped with an M4/M16/AR-15 type weapon to deliver more rounds more continuously, whether offensively or defensively, is not new. It dates back to the Vietnam War, when the original 20-round magazines were found inadequate and were replaced with 30-rounders.

Today, short of equipping every soldier or marine with a light machine gun, increasing fire continuity and volume for the M4 or M16 can be practically achieved in only two ways. The first is by having soldiers reload faster by minimizing the physical movements required to switch magazines. This is accomplished by attaching two or even three magazines together with various clips or clamps, or by storing the standby magazine close to the mag well in a holding device. The second is by having soldiers reload fewer times by using high-capacity magazines. Of these two methods of increasing firepower, it is more advantageous to use any magazine that holds more than 30 rounds. This is because every magazine change—even when the mags are coupled together—eats up a few precious seconds in releasing the empty mag, reloading with a full mag, and reacquiring the target before re-engaging. A higher-capacity magazine reduces a soldier's cumulative reload down time, during which the enemy may be able to reposition, reload, or fire on the soldier or his teammates. Reduced downtime increases a soldier's ability to continuously engage one or more targets, which improves suppressive fire capability and increases opportunities to disable the enemy.

However, with a single exception, all of the currently available solutions to the M4/M16/AR-15 variant firepower enhancement goal are not without issue. Specifically:

  • 40-round magazines do not provide a great enough capacity increase, and the long semi-oval spring is subject to binding and breaking.
  • Clipped-together magazines still must be released from the mag well, the loaded mag still must be inserted, and the target still must be reacquired before re-engaging. Furthermore, the open end of the stand-by magazine is exposed and subject to fouling by dust, dirt, or mud, and its feed lips are subject to impact damage. Placing a protective cap on the extra magazine defeats the quick-change purpose of the coupling device.
  • With a magazine holding device, the empty mag still must be released, the loaded mag still must be inserted, and the target still must be reacquired before re-engaging.
  • The 90+ round drum magazines are complex, difficult to take apart and clean in the field, typically requiring special powder lubricants. They often cannot remain loaded for long periods, are bulky, and one version has a center of gravity significantly off the vertical plane of the rifle, making it difficult to use for right-handed shooters.

The single exception to everything mentioned above is SureFire's new High-Capacity Magazines, which provide the warfighter with 60 or 100 rounds of ammunition in one tough, reliable, easily carried quad-to-double-stack magazine. Aside from the previously discussed tactical advantages of high-capacity magazines, the benefits provided by this new SureFire magazine are extensive:

  • Simple design does not require dry lubricants for reliability
  • Patent-pending design and high-quality coil springs prevent binding, fatigue, and breakage
  • Only 1.66" thick, significantly less than two clipped together standard magazines
  • 60-round magazine is about the same length as two clipped together 30-round magazines and it fits in most dual-mag pouches
  • Both 60- and 100-round magazines are less bulky and easier to store and transport than drum magazines
  • May remain loaded for extended periods of time without fatiguing the springs
  • Compatible with all M4/M16/AR-15 variants, including most STANAG 4179 compliant weapons
  • Weight of magazines is centered under the weapon
  • Normal shooting grip and stance are possible
  • Easier to hold and manipulate with one hand, compared to drum magazines
  • Both 60- and 100-round magazines (fully loaded) may be easily seated in the weapon with the bolt forward
  • Reliable functioning due to inherently simple feed system

Extremely robust, SureFire High-Capacity Magazines are precision-fabricated in America from 6000-series aluminum.


The images below are of the SUREFIRE HCM MAG5-60 and a 30 round CProducts LLC magazine





I recently noticed Brownells had the SUREFIRE HCM MAG5-60 available so as can be expected I ordered one. I havent had a chance to test it out though but Im hoping to get to that soon.


The SureFire high-capacity magazine for 5.56x45 mm (.223 Remington) ammunition, also available in a 100-round version, is compatible with M4/M16/AR-15 variants and other firearms that accept standard STANAG 4179 magazines. Constructed from Mil-Spec hard-anodized aluminum, they feed smoothly and reliably due to optimal geometry, non-binding coil springs, and ingenious nesting polymer followers. The long-lasting springs are cadmium coated for low friction and excellent corrosion resistance. Magazines require no lubricants and can be easily disassembled without tools for cleaning.

SureFire High capacity magazines provide distinct tactical advantages: increased initial firepower in ambush situations; fewer reloads overall, which means less downtime and target distraction in a firefight; fast and easy magazine insertion, even with a closed bolt; less bulk compared to drum mags, enabling a normal weapon grip. The 60-round magazine—slightly thinner than two 30-round magazines clipped together and about the same overall length—fits in most dual magazine pouches, eliminating special carry pouches required for drum magazines.

  • Compatible with all weapons that accept standard STANAG 4179 compliant magazines
  • Reliable functioning due to mechanical simplicity and high-quality non-binding coil springs—no lubricants required
  • Long-lasting springs are cadmium coated for low friction and excellent corrosion resistance
  • Easily seated in weapon with bolt forward
  • May be kept fully loaded for extended periods without spring fatigue
  • Only 1.66" thick, less than two 30-round magazines clipped together
  • 60-round magazine is approximately same length as two 30-round magazines clipped together
  • 60-round magazine fits in most dual-mag pouches



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