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Can the FN MK17 SCAR-H (SCAR-Heavy) 7.62mm Common Receiver and 5.56mm Caliber Conversion Kit Save the SCAR Program?

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By Chen Lee a.k.a. “SMGLee”
(Edited by David Crane)
defrev (at) gmail (dot) com

July 16, 2010

Some have said the SCAR is dead (at least the MK16 SCAR-L variant), but from the start of the SCAR program (PDF format document link), its goal has been a receiver that can handle both the 5.56mm NATO (5.56x45mm) and 7.62 NATO (7.62x51mm) cartridges. So, as the various AR manufactures complained, the FN MK16 SCAR-Light (SCAR-L) and FN MK17 SCAR-Heavy (SCAR-H) (PDF format) were born to make the competition more achievable by the industry. As the MK16 SCAR-L won the initial contract, the planned evolution of this weapon was for it to employ a multicaliber single receiver, better know as the “common receiver”. This explains the recent decision to run with the Mk-17 and use a 5.56mm adapter kit/conversion kit for it and to produce a common receiver/multicaliber weapons platform.

The ball for a new combat rifle for SOCOM (USSOCOM) started rolling in the late 90s, and over time, this ball would roll into what would eventually become the the now famous SCAR program (PDF format) on the heels of a solicitation that was released shortly after 9/11, when funding began to pour into SOCOM. From the start, the SCAR weapons concept was to be developed to include a combat rifle and sniper variant in both 5.56mm and 7.62mm calibers. However, once FN Herstal/FNH USA won the contract, and evaluators discovered during one of the test cycles that the MK16, outfitted with with FN’s standard hammer-forged, chrome lined barrel, was capable of shooting 8-inch (8″) 10-round groups at 800 yard during one of the testing cycle–yes that is ten rounds at 800 yards, all funnelled into an 8″ group–the idea of developing a 5.56 sniper variant was cancelled. This freed SOCOM up to concentrate on the Mk16, Mk17, and Mk20 SSR (Sniper Support Rifle) with a SCAR-PR (Precision Rifle), or the so called “Shroud” as the DMR (Designated Markman Rifle). So, when SOCOM decided to move the development funding for the the Mk-16 and Mk-17 and roll it into the Mk17 with a common receiver, it was also part of the cycle of development, but that announcement created the appearance of the MK16 program’s cancellation, and resulting reportage with that interpretation

Editor’s Note: DefenseReview does not necessarily agree with the author’s interpretation of recent events. We don’t necessarily disagree, either. We’re just not sure, yet. The fact is, the MK16 SCAR program is effectively cancelled at present, if only temporarily, before the MK17 SCAR common receiver solution is implemented and subsequently adopted in large numbers (if it’s eventually adopted in large numbers). Time will tell.

Some might say the MK17 platform is too large and heavy for the 5.56mm cartridge. However, the Mk17 utilizes a 7000-series extruded-aluminum (sheet metal) receiver with a monolithic rail system and brace-welds (brace welding). If you make this receiver a common receiver and offer a 5.56mm caliber conversion kit, thus turning the weapon into a 5.56mm platform, you’ve really only added about an inch (1″) in length to the existing Mk16 receiver (increasing your usable real estate) and a half pound (.5 lbs) in weight, with slightly more plastic on the trigger housing. You’re still running the same barrel and folding/telescoping buttstock configurations as the MK16. The bolt carrier group, of course, must be changed to run the 5.56mm cartridge. So, even though, in the end, a 5.56mm-converted Mk17 weighs a half pound more than the dedicated Mk16 SCAR-L, it’s still a lightweight system, especially compared to the Remington ACR (Advanced Combat Rifle), formerly known as the MagPul Masada in prototype form.

Some have noted that the Mk17 has experienced short-stroking problems when fired off-hand or if the weapon wasn’t held in a secure fashion. This is true, but no one ever explained the reason for this. The current crop of standard-issue 7.62x51mm ammo within the inventory (like M80 ball, utilizing a 147gr bullet) wasn’t designed to shoot in a 13.5-inch (13.5″) or 16-inch (16″) barrel. so a program to develop a 7.62mm NATO round that will support and optimize the SCAR/Mk17 platform was started, called SOST (Special Operations Science and Technology). The SOST program initially yielded a .308 Win. round that weighed in at 135gr (remember, the standard M80 ball round weighs 147gr) and it was also down-loaded to ease some of the complaints coming in that a lightweight (but of course too heavy as a 5.56mm rifle) Mk17 was recoiling too hard. This new ammo wasn’t really field-tested thoroughly before being deployed with the Mk17 into unit evaluation and combat. This bit of misstep caused the rumors to run amok about how unreliable the MK17 has been, especially when fired off-hand, and not securely from the shoulder. But I have personnally witnessed an operator firing standard M80 7.62mm NATO ball ammo through a MK17 while holding only the pistol grip and vertical foregrip with the gun out to the side. The weapon shot fine, magazine after magazine. So, stories about the Mk17 short-stroking seem troubling only until one knows the whole story behind it.

So, is the FN MK16 SCAR-L dead? NO (Editor’s Note: Both the Defense Review editorial staff and Kit Up! maintain the opposing position: that the MK16 has indeed been effectively cancelled, at least for the indefinite future). Many operators want the FN MK17 SCAR-H battle rifle/carbine/SBR (Short Barreled Rifle) as a new capability for the warfighter in the 7.62mm/.308 trim, not as a replacement capability for the already-proven (battle-proven) Colt M4/M4A1 Carbine and MK18 MOD 0/ M4 CQBR (Close Quarters Battle Receiver) SBR 5.56mm/.223 Rem. systems. The Mk17 will introduce a new capability that SOCOM warfighter hasn’t had, to date: a modern 7.62mm/.308 battle rifle/carbine/SBR that’s lightweight, modular (with hot-swappable barrels), reliable, and accurate. Is the Mk-16 better than the M4/M4A1? NO. The Mk16 does not provide a measurable or significant increase in combat capability or any lethality advantage over the M4/M4A1 carbine/rifle platform, so many operators have asked the following question: Why replace a good-capability weapon system with a proven track record and a high degree/level of end-user satisfaction, a weapon that has benefited from continued, long-term product improvement and evolution cycles over the past 20 years, with a brand new, unproven weapon system (FN MK16 SCAR-L) that does not really provide any real increase in combat performance?

Remember, the Colt M4/M4A1 Carbine platform came out around the late 1980s, and continued product development and improvements over the past twenty years made it one of the most capable and reliable 5.56mm weapons in the world. So, the redirection of funding to the MK17 7.62mm platform was inevitable. SOCOM will therefore be taking two of the best combat rifles into the Global War on Terror (GWOT) for the foreseeable future: the famed M4/M4A1 and the new kid on the block, the Mk17. The question is, will the M4/M4A1 be replaced someday by the SCAR? The answer is most likely YES! The M4/M4A1 will be replaced not because the Mk17 with the 5.56mm conversion kit is more reliable, or because it performs better (it doesn’t), no sir. The MK17 multicaibler weapons platform will most likely replace the M4/M4A1 because some bean counter in Washington will eventually figure out he does not have to buy a new M4 or M4A1 Carbine in order to shoot 5.56mm ammo at the enemy. He can instead just buy a 5.56mm conversion kit for the MK17 at 1/4 of the cost of the M4/M4A1, and the Mk-17 will be able to shoot the same 5.56mm ammo (62gr M855A1 “Green Ammo”, 77gr MK262 MOD 1, 70gr 5.56 Optimized a.k.a. “Brown Tip” ammo with Barnes solid copper Triple-Shock (TM) X Bullet a.k.a. TSX Bullet technology, 62gr MK318 MOD 0 SOST, you name it). The M4/M4A1 AR platform weapons will not be replaced because of their performance capabilities or lack thereof. They will ultimately be replaced because of the allmighty dollar! That’s it. The FN MK17 5.56mm conversion kit will simply be more cost-effective, i.e. cheeper…and that, ladies and gentlemen will be that.

Editor’s Note: DefenseReview will be updating this article with hi-res photos from the author, Chen Lee, soon.

Company Contact Info:

FN Herstal USA (FNH USA) Military Operations
PO Box 896
McLean, VA 22101
Phone: 703-288-3500
Fax: 703-288-4505

FNH USA Military Training Operations
Phone: 1-540-752-6200
Fax: 1-540-752-0967

© Copyright 2010 All rights reserved. This material may not be published, broadcast, rewritten or redistributed without receiving permission and providing proper credit and appropriate links.

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Can the FN MK17 SCAR-H (SCAR-Heavy) 7.62mm Common Receiver and 5.56mm Caliber Conversion Kit Save the SCAR Program? by

About David Crane

David Crane started publishing online in 2001. Since that time, governments, military organizations, Special Operators (i.e. professional trigger pullers), agencies, and civilian tactical shooters the world over have come to depend on Defense Review as the authoritative source of news and information on "the latest and greatest" in the field of military defense and tactical technology and hardware, including tactical firearms, ammunition, equipment, gear, and training.

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