Mk16 Mod 0 clone build: SOCOM's FN SCAR-L, part by part

On 24 May 2009, Rangers from 1st Battalion, 75th Ranger Regiment lined up on the infield before the Coca-Cola 600 in Concord, North Carolina, FDE SCARs slung muzzle down. Commons files them as SCAR-Ls, and the one magazine in view is curved, so these look like Mk16 Mod 0s, SOCOM's 5.56mm SCAR-L. They'd been fielded only weeks earlier.

Thirteen months later, Military.com reported that SOCOM would stop buying them after 850.

You can't buy the issued rifle, but FN's semi auto SCAR 16S gets you close.

What a Mk16 Mod 0 clone copies: SOCOM's 5.56 SCAR

Your clone copies the Rifle, 5.56 mm MK 16 MOD 0, the light half of SOCOM's SOF Combat Assault Rifle program. It's a select fire, flat dark earth FN carbine with three barrel lengths.

A short stroke piston drives the carrier. The one piece aluminum upper carries a full length top rail, and the polymer trigger module takes M16 pattern grips and magazines. The stock folds and the barrels are quick change.

Not the Geissele Mk16 rail

Search for Mk16 and you'll often get Geissele's Super Modular Rail, the handguard on the M4A1 URGI. All 42 GunPartPicker site searches containing mk16 from 29 June to 27 September 2026 were for Geissele parts. So were all 13 Google impressions we got for mk16 queries from 29 June to 24 September.

For the rail, read our guide to the Geissele Mk16 rail on the M4A1 URGI. Everything below is FN's rifle.

Mk16 SCAR history: 2004 contract to 2013 divestment

SOCOM wanted one modular family, specified and tested by operators, to stand in for a spread of 5.56 and 7.62 rifles. FN Herstal won the contract on 5 November 2004, less than 10 months after the solicitation. Army Times put the initial award at $634,390.

Testing ran from August 2005 to September 2008 and fired more than two million rounds, by FN's count. SOCOM's 2006 brief called the light rifle the EX16.

In the Army's extreme dust test at Aberdeen in late 2007, ten rifles of each type fired 6,000 rounds apiece. Ten SCAR-Ls logged 226 stoppages. Ten M4s logged 882.

Fielding with the Rangers in 2009

A five week field assessment by SOF operators in late 2008 rated the Mk16, Mk17 and Mk13 grenade launcher operationally effective and suitable. FN says fielding began in early April 2009.

Army Times reported on 12 May 2009 that about 600 Rangers would soon take the SCAR into battle, the first 600 of 1,800 rifles. It didn't split them between Mk16s and Mk17s.

Kit Up later said, naming no source, that SEALs got more Mk16s than any other SOCOM unit. We couldn't confirm a single Navy photo as a Mk16.

A Navy SEAL carries a suppressed SCAR on a desert ridge on 23 October 2009, the year the Mk16 and Mk17 began fielding; the caliber can't be read, so the photo doesn't show whether this rifle is a Mk16 or a Mk17. U.S. Navy photo 091023-N-2959L-174, public domain, via Wikimedia Commons.

Why SOCOM stopped buying the Mk16

Ten weeks after Milestone C approved production on 14 April 2010, Military.com's Kit Up reported that SOCOM would stop buying the Mk16 at 850. Its fiscal 2011 money would buy more Mk17s instead.

A SOCOM email in the report said the Mk16 didn't beat the M4 by enough to justify limited funds. The email didn't cite reliability.

FN pushed back in July 2010. In June 2011 a USASOC brief planned to divest the Mk16 and buy 5.56 kits for the Mk17. The Firearm Blog reported removal would run from late 2011 to 2013.

Back in June 2010, Kit Up had heard that units would hand their Mk16s back after deployment and pick up their old SOPMOD M4s or HK416s. To build one of those, start with our SOPMOD Block II M4A1 or CAG HK416 clone build. The Mk17, the Mk13 launcher and the later Mk20 stayed.

Mk16 variants: CQC, S and LB barrels

The manual says you change a Mk16's length by swapping the barrel or the whole receiver assembly. SOCOM's 2006 brief lined the three barrels up against the rifles they'd replace: the Mk18 CQBR, the M4A1 and the Mk12 SPR.

No source we found says which length units carried most, and no service photo of an 18 inch Mk16 turned up.

Mk16 CQC: the 10 inch close quarters barrel

The 2006 brief measured the CQC barrel at 9.96 inches, and the manual lists 10. It was the Mk16's answer to the Mk18 Mod 0 CQBR, at 6.99 pounds unloaded. Your route is FN's 10 inch 16S barrel assembly, which makes the rifle an SBR.

Mk16 S: the 14 inch standard

The manual calls the S the standard configuration. The 2006 brief measured its barrel at 13.82 inches, and it weighs 7.24 pounds unloaded. It was slated to replace the M4A1, the carbine our M4A1 SOPMOD Block I guide covers. With irons, the manual rates it to 300 meters on point targets and 500 on area targets.

Mk16 LB: 18 inches with a bipod

The 2006 brief lined the 18 inch LB up against the Mk12, the rifle in our Mk12 Mod 0 SPR guide, and it weighs 7.74 pounds unloaded. Only LB rifles got 20 round magazines and FN's bipod, P/N 314-905-0010.

The bipod folds and cants, with independent legs and a 1913 thumbscrew mount, and we found no record of its maker. We don't carry it, and we found no 18 inch 16S barrel in our feeds.

Muzzle velocity by barrel, M855 and Mk262

The manual gives velocities for two loads, and they show what each inch buys you.

Mk16 vs Mk17: telling the two SCARs apart

Our Mk17 Mod 0 SCAR-H clone build covers the 7.62 sibling. Once the Mk16 was on its way out, USASOC bought 5.56 conversion kits for its Mk17s, so a 5.56 SCAR photographed after 2011 may well be a converted Mk17.

Owners say the kit puts a Mk16 bolt and barrel in the Mk17 upper, with its own lower, carrier, firing pin and recoil spring. They spot it by a magazine release set further aft than a Mk16's, and by the photo's date.

A self described SOCOM armorer in the clone thread says Rangers were the only unit he saw using the kits on deployment. He also says Mk16 barrels wore AAC flash hiders and Mk17s wore FN's.

A Ranger from B Company, 2nd Battalion, 75th Ranger Regiment fires a SCAR on a close quarter marksmanship range at Fort Hunter Liggett, California, on 25 January 2014, after the Mk16 divestment USASOC planned to finish by 2013, so a SCAR this late isn't proof of a Mk16. U.S. Army photo by Pfc. Rashene Mincy, 55th Public Affairs Company (Combat Camera), public domain, via DVIDS.

How to build a Mk16 clone: start with a SCAR 16S

The service Mk16 is a machine gun, so your clone starts with FN's semi auto SCAR 16S. It brings the upper, trigger module, stock, carrier and sights, but its 16.25 inch barrel matches no Mk16 length.

No 16S had an in stock offer in our merchant feeds on 27 September 2026. Our builder has no SCAR platform yet either, so buy the rifle complete and use the one click box at the top for the optic, light, laser and the rest.

Pick a 16S made before August 2021

FN announced non reciprocating charging handles for the 16S, 17S and 20S on 31 August 2021. The Mk16's handle rides with the carrier, so buy a 16S built before that change and skip FN's NRCH conversion kit.

Buy FDE, FN's listed Mk16 finish. Owners say commercial uppers have drifted from greenish tan to gold, which looks different from the flatter FDE in service photos.

Why the 2026 next generation 16S looks wrong

FN's redesigned 16S, announced on 15 January 2026, adds an extended M-LOK receiver, AR grip compatibility and a hydraulically buffered two piece carrier. It keeps non reciprocating handles and wears a compensator. None of that was on a Mk16.

Mk16 parts list: the issued part and what to buy

Here's every slot we could document, built from the manual and federal catalog records and checked against owner reports and our merchant feeds.

Product photography is supplied by the listed merchants through their affiliate feeds. The AAC 51T hider and M4-2000 can had no in stock offer on 27 September 2026.

Exact is the issued part or its commercial twin. Equivalent does the same job with the same look, and budget is a cheaper lookalike. On host comes with your 16S, hunt means we don't stock it yet and unobtainable means you can't buy it.

The lower receiver group

On a SCAR, the lower is a polymer trigger module housing, and everything in this group arrives on your 16S.

An FN SCAR-L marked FN Herstal Belgium, field stripped into the groups this guide covers: the aluminum upper with its barrel, the polymer trigger module and grip, the side folding stock, the bolt carrier group and recoil spring, plus three magazines and a sling; it isn't identified as a SOCOM Mk16. Photo by The RedBurn, CC BY-SA 4.0, resized, via Wikimedia Commons.

Lower receiver: the FN trigger module

The issued module is polymer, with an ambidextrous selector marked S, 1 and A, an ambidextrous magazine release and a bolt catch. There's no burst. The trigger breaks at 6 pounds, give or take 1.5.

Keep your 16S's semi auto module. Skip the Geissele Super SCAR trigger and Magpul SSG selector, which no source we found puts on an issued Mk16.

Stock: FN side folder with cheek rest

The issued stock telescopes through six half inch positions, and its cheek rest raises the comb 0.51 inches. It folds right, locks into the brass deflector and has an ambidextrous rear sling point.

Owners say early black latch buttons could shear, so FN revised the latch and later buttons are FDE.

Grip: FN polymer pistol grip

The manual lists the grip as part of the trigger module, and Wikipedia calls it M16 compatible. The self described armorer quoted earlier posted a Mk17 grip fitted to an M4A1, so they cross over. No merchant in our feeds sells FN's grip on its own, so keep your 16S's.

The upper receiver group

A SCAR's gas block and folding front sight come fitted to the barrel, and it has no handguard. That's why one enthusiast Mk17 parts list marks those AR style slots N/A or none.

Upper receiver: FN monolithic aluminum, FDE

The issued upper is hard anodized monolithic aluminum in FDE, with a continuous 12 o'clock 1913 rail and 3, 6 and 9 o'clock rails up front. It's the serialized part, so it comes with your 16S. No owner has documented Mk16 production colors.

Barrel and gas block: FN 14 inch S or 10 inch CQC

Issued barrels are cold hammer forged, chrome lined and free floating, with a 1 in 7 twist and six grooves. The gas block holds a short stroke piston and a regulator set at 12 o'clock unsuppressed, 10 o'clock suppressed and 4 o'clock for disassembly.

FN's 16S assemblies, 14 inch P/N 98804 and 10 inch P/N 98802, arrive with the front sight, gas block, regulator, piston and flash hider fitted. A retailer lists 1/2x28 threads, and the 16S regulator has two positions.

Both cards are equivalents, and either makes your 16S an SBR, so check your state's SBR rules first. KY Gun Company had them at $1,132.23 and $1,143.91 when we checked.

Muzzle device: AAC 18T Blackout flash hider

The manual describes a hider with a geared rear whose teeth catch the suppressor's spring wire latch. That matches AAC's 18 tooth Blackout. That armorer and the clone thread's parts list name it for the Mk16, so treat the maker as owner testimony.

The 18T is out of production, and a 2025 post warned of a rewelded demil Mk17 hider, so inspect any surplus one. Cloners use AAC's 51T Blackout as a lookalike, though owners say its latch mount differs from the 18T's spring clip.

Our 51T card is an equivalent, and it had no offer when we checked.

Rails and panels: FN cover kit, TangoDown stand ins

The Mk16 has 1913 rails at 3, 6, 9 and 12 o'clock and no handguard. FN's issued cover kit, P/N 314-899-7080, held eight panels: one 6.75 inch, three 4.125 inch and four 2 inch.

Cloners name TangoDown, which sells SCAR panels as SC-004 (4.125 inch), SC-002 (2 inch) and SC-006 (6 inch). We don't stock them, so our cards are TangoDown's FDE rail cover, an equivalent, and Magpul's FDE XTM panels for budget.

Bolt carrier group and reciprocating charging handle

FN's moving parts are the bolt, carrier and return spring, with the charging handle on the carrier, left or right. The manual warns that the handle reciprocates and says to put optic throw levers on the other side. A 16S built before August 2021 matches, so skip NRCH and 2026 carriers.

Iron sights: FN folding front and rear

The front sight folds on the gas block and the rear aperture on the top rail, with a 16.18 inch sight radius in the manual's table. Your 16S has the rear, and each FN barrel assembly has the front.

Optics, lasers and lights on the Mk16

No optic, laser or light was basic issue. The manual's Additional Authorized List names what units could mount, and no source says which optic Mk16s carried most.

Optic: EOTech, ACOG and ELCAN on the authorized list

Catalog records put commercial names to five of the authorized optics.

Our exact card is the TA01, sold today as the TA01NSN. The tan 553 is discontinued, so a tan EXPS3-0 stands in for it.

The tan G33 covers the 3x magnifier on the clone thread's list.

Laser: AN/PEQ-15 and civilian IR stand ins

The authorized list gives the LA-5/PEQ, the AN/PEQ-15 in common usage, plus the AN/PEQ-2 and AN/PEQ-5. All three are military only. The Rangers at Concord in May 2009 carried tan rail mounted units with pressure switch cables, model unidentified.

The civilian ATPIAL-C in tan was out of stock across our feeds, so our card is a budget Holosun LS321G in black. Our IR laser buyer's guide compares the rest.

Light: SureFire M900 and Insight M6X

Catalog records tie the authorized Visible Bright Light II to SureFire M900 series part numbers. The gun lights printed as SU-232/PVS and SU-238/PVS carry Insight M3X and M6X part numbers.

The Insights are discontinued, and the only M900s in our feeds were used trade ins, out of stock. Your budget stand ins are SureFire's tan M640DF and Streamlight's FDE TLR-1 HL.

Issued accessories and basic issue items

The basic issue list gave each Mk16 ten steel magazines, a vertical grip, a rail cover kit and a sling. It also listed a blank firing adapter, tool and cleaning kits and its own suppressor. LB rifles added a bipod and 20 rounders.

Suppressor: the issued can and the AAC SCAR-SD

The manual lists Suppressor, 5.56 mm, MK 16, NSN 1005-01-556-4261, locked over the flash hider by a spring wire latch. It weighs 0.5 pounds in the manual's text and 0.99 in its table. The federal catalog record, assigned 3 October 2007, shows part number SCARL001 and no maker.

Owners call it the AAC SCAR-SD, though no document backs that. Our AAC M4-2000 card is an equivalent with no in stock offer when we checked. Owners say first generation M4-2000s used an 18 tooth mount, so check which mount yours takes, and that your state allows suppressors.

Foregrip: FN vertical grip and TangoDown

FN's issued grip, P/N 314-900-0010, clamps to the 6 o'clock rail with twin spring locking bars. It has a pressure pad recess and a waterproof storage compartment. Cloners name a tan TangoDown, model unconfirmed. Our TangoDown cards, full length and MK46 short, are equivalents.

Sling: FN one inch with rail swivels

The issued sling, P/N 314-910-0030, is one inch nylon with spring hooks on two rail swivels, P/N 314-912-0010. Owners say FN sold a tan one at retail as 98824 and that VTAC slings were common in photos. We list FN's 98824 in FDE, out of stock on 27 September, and VTAC's coyote MK1 sling in stock. The coyote Magpul MS3 Gen2 is your budget stand in.

Magazines: ten FN steel 30 rounders

Each rifle got ten FN steel 30 rounders, P/N 314-601-0020, and the manual says standard M4 and M16 magazines fit too. FN's steel SCAR 16S magazines in FDE and black were out of stock across our feeds on 27 September 2026. We card the FDE one anyway, since it's the commercial version.

Polymer magazines vary, so check the maker's SCAR compatibility before you buy.

Mk13 EGLM: the grenade launcher, not the sniper rifle

In the SCAR system the Mk13 Mod 0 is the 40mm Enhanced Grenade Launcher Module, the FN40GL in Wikipedia's naming. It fits the 6 o'clock rail on any barrel. It has nothing to do with the Mk13 Mod 5 sniper rifle, and it's military issue, so we don't list it.

The civilian legal path to a Mk16 clone

The issued Mk16 is a machine gun. Your clone is a semi auto 16S, and the barrel you pick decides which rules apply.

A 10 or 14 inch barrel: SBR rules and state law

A 10 or 14 inch barrel with a stock makes a short barreled rifle. ATF announced on October 9, 2026 that it would stop enforcing Form 1 and Form 4 approval and registration for SBRs, though it still accepts both at $0 if you want yours registered. Some states ban SBRs outright, others only allow registered ones, and taking one across state lines needs approval on ATF Form 5320.20 first.

Form 1 markings go on the upper receiver

A SCAR's serialized receiver is the aluminum upper, so if you register it on Form 1, your maker markings get engraved there. The polymer trigger module doesn't carry them.

Pinning and welding a 14 inch barrel past 16

A permanently attached muzzle device, pinned and welded, counts toward barrel length. The total must reach 16 inches, with at least 26 inches overall. SCAR barrels are built to swap, so have a gunsmith do it properly.

You keep FN's 14 inch barrel and skip SBR paperwork. The factory 16.25 inch barrel skips it too, but it matches no issued length.

Suppressors, state bans and select fire parts

A suppressor is an NFA item, though ATF announced on October 9, 2026 that it would stop enforcing Form 4 approval for them, and some states ban them. Our suppressor guide covers current federal rules and tax.

Select fire modules and auto sears are machine guns, legal for civilians only as transferable examples registered before 1986. Pistol and brace rules have changed more than once, so we left that route out.

What you can buy today and what is unobtainable

We sorted every row in the parts list by what we could offer you on 27 September 2026.

Parts no retailer can sell you

The select fire Mk16 and its module are machine guns. No merchant in our feeds sells the issued can or FN's rail kit, vertical grip, issued sling, bipod, blank adapter or tools, and the 18T is surplus only.

The PEQ lasers and the AN/PVS-24, AN/PVS-17A and SU-232/PAS night sights are military issue. Insight's lights and the tan 553 are discontinued. We found no Mk16 UID label on record, so don't copy a Mk17's onto your upper.

What a Mk16 clone costs today

We priced an S configuration's add on parts from in stock offers on 27 September 2026. The total leaves out the 16S, the 51T hider and the can, since none of them had an in stock offer.

The 10 inch barrel adds $11.68, and a SpecterDR in place of the EXPS3-0 takes the total to $4,864.77. Your 16S and magazines come on top.

What the internet gets wrong about the Mk16

Popular articles miss dates, and clone threads miss parts. Here's what the records show.

Dates the cancellation stories get wrong

Military.com's page also says Naval Special Warfare sought a five year Mk16 purchase in 2011. We couldn't find anything to back it, so treat it as unverified.

Parts the clone threads get wrong

Sources and photo credits