"The US Special Operations Community has long had issues with the M4A1 Carbine
The Joint Operational Requirements Document (JORD) for the SCAR (Special Operations Forces Combat Assault Rifle) was approved in September 2003 and actual development and competition began in January 2004. After 10 months of development and competition between prospective manufacturers, a production contract was awarded to FN Herstal. The SCAR programme was unique in that it was developed with full input and participation from special operations forces of all four services. The SCAR will be manufactured in the US in FN Herstal's Columbia, South Carolina facility. In fact, most of the personnel involved in testing the SCAR prototypes were active duty special forces personnel.
There are two versions of the SCAR - the Mark 16 SCAR Light (SCAR-L) and Mk17 SCAR Heavy (SCAR-H). Both are essentially multicalibre modular carbines with 90 per cent parts interchangeability. The two SCAR variants replace five existing small-arms systems in the US Special Operations Community - the M4A1, the Close Quarters Battle Rifle (CQBR), the Mk12 Special Purpose Rifle (SPR), the M14 and Mk11 (SR-25). The SCAR was developed entirely using FN Herstal funding except for the government testing and the SCAR-H was demonstrated six months ahead of schedule, saving tax dollars and enabling the new weapons to get to the troops who need them more expeditiously.
The SCAR carbines significantly improve the overall performance of their predecessors. The SCAR stock both telescopes and folds. The telescoping feature is necessary for adapting the length of pull for different personal equipment configurations, armour, or clothing that may cause changes in the position of the carbine with respect to the distance between the user's shoulder and trigger. The folding stock is a preferred option because special forces operators must be able to conceal their carbines under clothing and fire them with the stock folded. The folding stock also enhances operations from vehicles, helicopter insertions, parachute operations and other missions. The SCAR cheekpiece is sloped and adjustable so that the user has the capability to tailor the stock to their body and aid in obtaining the proper eye relief regardless of the optical sight mounted.
Getting a grip
The SCAR pistol grip was developed using extensive anthropometrical measurements to determine the best overall design and size to suit most users. Adapters are available so that individual users can modify the pistol grip to suit their hand size - from small to large. The redesigned pistol grip offers better control and more positive engagement of the controls.
The SCAR fire controls are optimised for easy engagement. The selector switch moves from safe to semi-automatic to full automatic and return to safe in only 90o and is fully ambidextrous instead of the 180o throw of the M4A1 selector switch that is not ambidextrous in its 'as-issued' configuration. Like the selector switch, the SCAR magazine release is fully ambidextrous and protected on both sides against inadvertent release. The bolt release is also ambidextrous and optimised for all hand sizes. Not only is the charging handle ambidextrous, but also serves as a forward assist mechanism and backup bolt release. The SCAR's cyclic rate is only about 600 to 650 rounds per minute versus the M4A1's 900 rounds per minute. This not only facilitates weapon control, but enables the user to squeeze off short bursts by trigger control. There is no need for a burst-fire feature.
The SCAR tappet gas system is a departure from that of the M4A1 and resolves a problem that has plagued the AR family since its original design - fouling and particulate matter being blown directly back into the receiver. Not only does this make for a very 'dirty' gun that requires fairly intensive maintenance, but with the wrong powder excessive fouling can actually cause stoppages. This was the case when the original M16A1s were fielded. The US Army specified the wrong powder and in the crucible of Vietnam, many soldiers and Marines lost their lives when their rifles ceased to function due to excessive fouling. This problem was resolved nearly 40 years ago, but the M16 rifle and M4 carbine still get a blast of hot gases and fouling with every shot fired. Nearly as bad, the hot gases and fouling directed into the AR's receiver cause the weapons to rapidly heat up under full automatic-fire conditions. This is not much of an issue with semi-automatic only guns, but with Special Forces carbines that are frequently fired extensively on full automatic, heating is critical.
The SCAR tappet impacts against the upper operating rod portion of the bolt carrier and drives it to the rear, unlocking the bolt via a cam. Excess gases and fouling are vented into the air.
We fired several hundred rounds through the SCAR-L to see just how well the gun stood up to heavy use and the receiver did not become hot, as would have been the case if we were shooting an M4A1 or M16. In addition, the SCAR gas system is consistent regardless of barrel length, because the distance of the gas port from the receiver is the same. This makes the SCAR less susceptible to function problems with suppressors and different types of ammunition. Just as important to the user is the fact that the SCAR family is much easier to clean and maintain than the M4A1.
The SCAR's monolithic MIL-STD-1913 rail system provides an uninterrupted top surface for mounting optical sights and night-vision optics such as the recently adopted AN/PVS-22 Universal Night Sight. Of course, both SCAR versions are fully compatible with all SOPMOD components. The SCAR monolithic rail forend also free floats the barrel, a factor that enhances accuracy. Because the barrel has a quick-change feature, users can change barrels in a matter of minutes, varying the length to mission profile. Standard barrel length is 353 mm, while a 251 mm barrel is optional for CQC/entry work and a 457 mm barrel can be mounted when optimum accuracy is desired. Since the barrel can quickly be changed, the capability exists to change calibres as well. The recently developed 6.8 x 43 mm can be adopted by simply changing barrel, bolt head and magazine in only a few minutes, where converting an M4A1 to 6.8 mm involves changing the entire upper receiver, which is much more expensive, not to mention the need to maintain entire upper receivers for conversion. In addition, it is envisioned that the Mk17 will eventually be available in 7.62 x 39 mm.
Headspace is fixed and is not affected when barrels are changed. Any type of ammunition that can be fired from an M4 or M14 can also be fired from a SCAR-L or SCAR-H. For example, some users are conjecturing about the possibility of using special-purpose cartridges such as the .50 Beowulf, a devastating close-quarters combat cartridge. All that would be required would be a barrel change.
Common ground
As mentioned, both SCAR variants have 90 per cent of their components in common - never before achieved in two rifles in calibres so divergent as the 5.56 x 45 mm and 7.62 x 51 mm. The only parts that are different for each SCAR variant are those that are calibre specific, namely the polymer lower, which must accept the 5.56 mm or 7.62 mm magazine, the barrel, the bolt head and the ejection port. Magazines are, of course, different. The Mk16 uses standard M16 magazines. The aluminium upper receiver is an extrusion that is identical for both carbine variants, except the size of the ejection port. Everything else interchanges. To put this achievement in perspective, it is the equivalent of taking an AR-15 and an AR-10 and making them share every component except lower receiver, bolt head, barrel and magazine.
The SCAR makes use of the most modern manufacturing techniques, keeping its cost on a par with the M4A1, despite its dramatic improvements in just about every way. The manufacturing process required a minimum investment in tooling and personnel training, since most processes are computer controlled. The unstressed upper receiver is an aluminium extrusion. The lower is likewise unstressed, lending itself to polymer construction. All stressed components are steel.
Production Mk16 and Mk17 carbines will be finished in colour, specifically FS595B Flat Dark Earth that is a good compromise colour for deployment in most environments. There are very few straight lines and very little black in nature, so special forces personnel have been camouflaging their weapons with common spray paint for years. The dark earth colour gives them a base upon which to build camouflage to suit their specific needs.
Magazine interchange
A further significant improvement over current small-arms systems involves the redesigned steel magazine that interchanges with current magazines. Not only are the SCAR magazines steel, but have been redesigned with modified feed lips and follower. The SCAR-H magazine externally appears to be a modified FAL magazine, but is totally different and will not function in a FAL, nor will FAL magazines function in a SCAR-H. Each version of the SCAR will be shipped with 10 magazines.
Sources within the special operations community have mentioned that the SCAR's reliability is literally AK-like, which if true, means that the SCAR is a quantum leap ahead of the M4A1 in this respect as well. As such, the SCAR barrel life is stated to be 35,000 rounds and the service life of the overall system is stated to be 90,000 rounds. Of course, when and if barrels are worn out, they can be replaced in minutes by removing two bolts. Mean number of rounds between stoppages is 2,000 rounds.
As if this were not enough, FN Herstal also developed a new underbarrel grenade launcher for the SCAR programme.
The new Enhanced Grenade Launcher Modular (EGLM) mounts to a MIL-STD-1913 rail beneath the SCAR barrel and opens to the side, allowing long 40 mm grenades to be inserted, a major shortcoming of the current M203. Like everything else about the SCAR, FN Herstal's new EGLM is ambidextrous and can be pivoted either right or left to chamber a round. The barrel locks via lugs and rotates to unlock when moved forward. The user can either eject the spent round or not. A stock is available so the EGLM can be used as a stand-alone. The EGLM fire control is state of the art and features a laser rangefinder with automatic elevation built in. When the EGLM is aimed low, the sight reticle blinks red. If the round will go high, the reticle is constant red. If the EGLM is on target the reticle glows green. For hidden targets or those in defilade, the sight gives the distance to the target so it can be engaged. The EGLM sight is compatible with the latest programmable 40 mm ammunition that gives air bursts over targets.
Although we were unable to conduct in-depth accuracy testing of the Mk16 and Mk17 SCAR variants, we had the opportunity to shoot the Mk16 extensively and to examine and fire a few rounds through the Mk17 SCAR-H at FN Herstal's Virginia, US facility. We adjusted the Mk16 using the adjustable stock and cheekpiece to achieve the optimum configuration for our shooting style. Controls were "just right" and in the appropriate location for access with either hand. Both variants were controllable on full automatic. The low cyclic rate enabled us to select bursts from three to five rounds or even single shots with ease. The first Mk16 SCAR-L carbines will be in the hands of Special Forces troops in late 2005.
M16 steps down
It has been a long time since the M16 was first modified into a carbine configuration - more than 40 years. The AR carbine has been a good servant during its lifetime, but all things must come to an end and the US service career of the M4A1 seems to be about over. The M16 is also apparently approaching the end of its service life.
The fate of the M4A1 is already sealed, however. The Mk16 will replace it and all other AR-derived small arms in the US special operations community, although it will be many years before the Mk16 replaces all M4A1 carbines.
Since the only difference between the M4 and M4A1 is one of burst-fire or full automatic capability, US units using M4s may also eventually replace them with Mk16s, since it is a significant improvement over any AR-derived small arm.
SPECIFICATIONS
Mk16 SCAR-LMk17 SCAR-H
Calibre5.56 x 45 mm basic
6.8 x 43 mm possible
.50 Beowulf possible
6.5 Grendel possible7.62 x 51 mm basic
7.62 x 39 mm
.300 WSSM or .300 RSAUM possible
Operation Gas, select fire Gas, select fire
Length, std configuration 620-848 mm, 769-995 mm
Barrel length Varies Varies
Empty weight 3.5 kg 3.85 kg
Cyclic rate 600 rounds/minute 600 rounds/minute
Magazine capacity 30 rounds standard, 100 rounds optional (C-Mag)
20 rounds (7.62 x 51 mm) 30 rounds (7.62 x 39 mm)"
Mk16 SCAR-L's stock can be folded to enhance operational flexibility (Source: Chris Rohling)
Mk16 SCAR-L with Enhanced Grenade Launcher Modular (EGLM) mounted. Unlike earlier M203, EGLM clamps to bottom MIL-STD-1913. EGLM opens to either right or left side allowing 40 x 46 mm grenades of any length to be fired (Source: Chris Rohling)
Mk16 butt-stock extends to adjust length of pull, folds and has adjustable cheekpiece to optimise shooter's cheek weld for any type of sight (Source: Chris Rohling)
EGLM dismounted and open for loading. EGLM may be opened to either side and locks via radial locking lugs. Unlike M203, EGLM can chamber and fire 40 x 46 mm grenades of any length, increasing operator flexibility (Source: Chris Rohling)
Prototype 5.56 mm NATO Mk16 SCAR-L (bottom) and 7.62 mm NATO Mk17 SCAR-H (top). Mk16 and Mk17 have 90 per cent parts commonality(Source: Chris Rohling)
Mk16 SCAR-L selector is fully ambidextrous and can be moved from 'safe' to 'full automatic' in 90o - half that of the M4. The short throw of the selector is an improvement in user ergonomics (Source: Chris Rohling)
)