If you watch in the video, during their 'patrol' the prone guys shoot with the rifle cocked at an angle, with some sort of optic mounted on that plane so they can sight.The 60 rounder looks like a winner to me, the 100 rounder is just too long to use in the prone postion.
That is a distinct possibility ...I wonder if these magazines are in response to the Marine Corps decision to replace their M249s with full auto M16 variants?
Corps Set to Field SAW Replacement
July 01, 2010
The Marine Corps will field its new, lightweight auto rifle this fall to five combat battalions preparing for war-zone deployments.
Commandant Gen. James T. Conway gave Corps officials the green light in April to issue approximately 450 M27 Infantry Automatic Rifles, enough to replace every M249 squad automatic weapon in four infantry battalions and one light armored reconnaissance battalion.
The limited fielding is a final test to find out if the Heckler & Koch-made weapon performs as well in an operational environment as it has in testing, said Charles Clark III, who oversees infantry weapons requirements at the Corps' Combat Development and Integration office at Quantico, Va.
"The battlefield test will be a verification of what we have already established through extensive operational testing," Clark said. "We want to get a user assessment prior to full-rate production."
Conway's decision comes despite his past concerns about replacing the M249 with a magazine-fed automatic rifle. His main worry is whether the M27's light weight and accuracy will be enough to make up for the loss of suppressive firepower Marine gunners will give up when they go into battle without the belt-fed M249.
Program officials acknowledge that a 30-round magazine cannot produce the high volume of fire the M249 is capable of when loaded with a 200-round belt. The Corps is considering high-capacity magazines that can hold 50 or 100 rounds of 5.56mm ammo, but Marines that deploy with this first batch of IARs will carry only 30-round magazines.
"The initial limited fielding will not include a high-capacity ammunition source, but that remains an option," Clark said, explaining that such magazines will have to undergo a separate round of testing.
The M27, a variant of the H&K 416, weighs just 7.9 pounds, unloaded. By comparison, the M249 weighs 17 pounds, unloaded.
Marines involved in operational testing at Twentynine Palms, Calif.; Fort McCoy, Wis.; and Camp Shelby, Miss., were "very comfortable with it because it's a lot like a M16A4 and it's far more maneuverable and portable" than the M249, Clark said. "The H&K gun has performed very well throughout operational testing."
Marine officials selected the H&K weapon in October over two prototypes from Colt Defense LLC and one made by FN Herstal. (Colt makes the M4 and FN makes the M249.) The M27 uses a short-stroke gas piston, which proved more reliable than the M16/M4's direct gas system in an Army dust test in late 2007.
The new IAR, which fires from the closed-bolt position, is most effective when employed as a point-target weapon, program officials maintain.
"The accuracy has been a real standout," Clark said. "The IAR has demonstrated to be a far more accurate gun" than the M249, which fires from the open-bolt position.
In the defensive role, the M27 used "far less" ammunition to drop the same number of targets compared to the M249, Clark said.
Program officials maintain that the increased accuracy will compensate for the M27's slower, sustained rate of fire. Unlike the M249, the new IAR doesn't have a spare barrel that can be switched out to prevent overheating. Marine gunners will have to keep their sustained rate of fire at 65 rounds per minute compared to the M249's 85 rounds per minute.
"It has a little bit lower sustained rate of fire, but it's far more accurate," Clark said.
The Corps hopes to begin fielding the M27s in November so Marine units have "four to six months" to train with their new weapons.
"We are not sending these guns straight to Afghanistan," Clark said. "The units that are participating will have the guns long before they go into theater."
Last time I got CProducts 30 rounders they were less then $8/mag. @ those prices you could buy 15 Aluminum mags for less then 1 Aluminum 60 rounder. HMMMMMM where to better spend my hard earned $? I know what I would invest in...a 60rnd magazine is a neat concept, but not $130 worth of neat!!!!dance2