Mk11 Mod 0 clone build: KAC's Navy SR-25, part by part

In May 2000 the Navy and U.S. Special Operations Command adopted a 20 inch SR-25 from Knight's Armament Company as the Mk 11 Mod 0. Its suppressor slides over the barrel and locks into the gas block, so the rifle has no muzzle device.

That detail decides how close your clone gets. We checked every slot against KAC's own manual, then priced what you can buy today.

What a Mk11 Mod 0 clone copies

A Mk11 Mod 0 clone copies the original Navy rifle. You're building a black KAC SR-25 with a fixed A2 stock, a 20 inch free floated barrel under KAC's quad rail, a Leupold 3.5-10x scope and the quick detach can. You'll also see it called the Navy SR-25 or the KAC Mk11.

Maj. Gen. Douglas V. O'Dell, commanding general of the 4th Marine Expeditionary Brigade (Anti-Terrorism), fires a Mk11 Mod 0 at Stone Bay, North Carolina, in March 2004. The Marine caption called it a Squad Advanced Marksman Rifle, but the lower is engraved RIFLE 7.62MM MK11 MOD 0 and KNIGHT'S MFG CO, VERO BEACH, FL. U.S. Marine Corps photo by Cpl. Sharon E. Fox, public domain, via Wikimedia Commons.

Mk11 Mod 0 specs from KAC's operator's manual

You'll only match the velocity and range figures with M118LR, the load the rifle was optimized for.

Mk11 Mod 0 parts list: the issued part and what to buy

Here's every slot, how well the records back it, and what you can buy in its place. We cross checked one enthusiast Mk11 Mod 0 parts list against the manual, and each part's section notes where they disagree.

The parts from this guide that we stock, laid out overhead. Product photography is supplied by the listed merchants through their affiliate feeds.

Exact is the issued part or its current version, equivalent a product doing the same job, budget a cheaper stand in and missing something we don't stock yet. Strong evidence means the manual or a Navy record names the part, and weak means one owner or the enthusiast list alone.

Mk11 sniper rifle history: from Stoner's SR-25 to SOCOM

Eugene Stoner developed the SR-25 at Knight's Armament in the early 1990s by pairing his AR-10 layout with M16A2 parts. You're cloning its 20 inch military form.

The Special Light Weight Match: KAC's 20 inch SR-25

The first SR-25 was a 24 inch match rifle with a fiberglass forend. KAC's David Lutz told Small Arms Review in 2006 that special operations troops took early rifles to Somalia and asked for a shorter barrel. KAC answered with a 20 inch rifle.

A forum member with ties to KAC says the operators wanted the shorter barrel so the rifle stayed manageable with a can. KAC called the result the Special Light Weight Match.

Adopted in May 2000 as a complete sniper system

The Navy and SOCOM adopted it as the Mk 11 Mod 0 in May 2000, per Small Arms Defense Journal. SOCOM wanted magazine capacity and faster follow up shots than a bolt action gave. For the SEALs' .300 Win Mag bolt gun, see our Mk13 Mod 0 clone build.

The Navy's stock number for the system, assigned 13 June 2000, lists the rifle with a magazine, backup sights, suppressor, bipod, scope and case. By November 2006 KAC said it had built over a thousand.

Who carried the Mk11: SEALs, SOCOM and the Marines

Navy SEALs used it. A 2011 USASOC planning slide showed Army special operations divesting Mk11s along with the 5.56 Mk12. You'll find that rifle in our Mk12 Mod 0 clone build and Mk12 Mod 1 clone build.

A Navy SEAL sniper pair in a hide. The Navy caption names the rifle of the SEAL on the right as a MK 11 Mod 0 and his partner's as a MK 15 Mod 0 .50 caliber rifle, and the camera date is 20 May 2004. U.S. Navy photo, Naval Special Warfare, public domain, via Wikimedia Commons.

The Marines mostly carried the Mod 1. A 2007 Flickr photo captioned as an Air Force combat controller with a Mk 11 Mod 0 is our only evidence of AFSOC use.

Mk11 variants: Mod 0, Mod 1 and Mod 2

Only the Mod 0 pairs KAC's free float RAS with the gas block can. Here's how the family and the Army's M110 differ.

Mk11 Mod 1: a Mod 0 lower under an M110 upper

The Marines ordered 180 rifles soon after the September 2005 XM110 award, KAC's Lutz said in 2006. They wanted the SASS barrel, flash suppressor and can, a URX type forend and a black finish. Marine Corps Times called the result the Mark 11 Mod 1.

In 2009 KAC offered the last 50 Mod 1s to civilians at a suggested $8,508, The Firearm Blog reported.

Scout snipers from the 26th Marine Expeditionary Unit line up their new Mk11 rifles before firing them for the first time at Fort A.P. Hill, Virginia, on 9 July 2006. The caption doesn't name the Mod, but the tan M110 type cans point to the Mod 1. U.S. Marine Corps photo by Lance Cpl. Aaron Rock, public domain, via Wikimedia Commons.

Mk11 Mod 2: the M110 under a Navy name

KAC's manual says the Mod 2 rifle is identical to the Army's SR-M110 apart from receiver markings. Its stock record, assigned 20 April 2009, lists Nightforce scopes for the Navy or Schmidt and Bender for the Marines, an adjustable stock and a flash suppressor. If you want that look, you're building an M110.

How the Mk11 led to the M110

KAC's winning XM110 started from the Mk 11 Mod 0. Lutz said its URX rail, flash suppressor, longer can, ambi selector and adjustable stock were all on the rifle that won on 28 September 2005.

Our M110 SASS clone build covers every change, and our M110K1 clone build covers KAC's 16 inch carbine.

The lower receiver group

KAC's manual lists the stock, grip, trigger guard, receiver extension and magazine catch among the M16A2 parts the SR-25 shares. So most of your lower is cheap GI hardware. Our AR-15 vs AR-10 parts guide covers what else carries over.

Lower receiver: KAC SR-25 with a non ambidextrous selector

The manual shows a KAC SR-25 lower engraved RIFLE 7.62 Mk 11 Mod 0, P/N 98169, with a left side selector only. Early rifles say Vero Beach, and the date KAC moved to Titusville is disputed.

The KAC card is today's SR-25 lower, out of stock on 27 September, and we can't confirm it keeps the Mod 0 pattern. Owners use the LMT MWS as a stand in, the MARS-H is LMT's ambi equivalent, and we haven't confirmed the budget PSA PA10 takes a KAC upper.

Trigger: KAC two stage, set at 4.5 pounds

Lutz said KAC used a simple two stage trigger set at 4.5 lb, though the manual doesn't name the model. The Mk11 fired semi auto only, so you've got no auto parts to replace.

We don't list a KAC trigger, so these are equivalents, with the Rise as the budget pick. Wikipedia notes the SR-25 hammer doesn't interchange with the AR-15's, so check fit with the maker before you order.

Stock: fixed M16A2 on the SR-25 rifle buffer

The Mod 0 used the M16A2 rifle stock, butt cap and spacer on an A2 receiver extension. Lutz said the Mk11 never had an adjustable stock. One owner lists KAC's SR-25 buffer and spring as PN 99133.

The A2 stock and tube are exact. The buffer and spring are equivalents, and we haven't carded KAC's own SR-25 action spring yet, though Brownells lists it.

If you'd rather follow the enthusiast list, it also lists a Magpul PRS, and owners report them on some rifles. The Mod 0 was issued the A2, and today's PRS is the Gen3.

Grip and trigger guard: standard M16A2 parts

The manual lists the M16A2 grip and trigger guard as common parts, so GI parts are exact. The enthusiast list alone adds an Ergo grip without naming a model, so we've carded the Tactical Deluxe as an equivalent.

The upper receiver group

The upper is where a Mk11 stops being an SR-25 with a scope. You'll source the rail, gas block, front sight and a true Mk11 barrel from surplus or small makers.

Upper receiver: SR-25 flat top with a clamp on deflector

The Mod 0 upper is a KAC SR-25 flat top with its case deflector clamped in rail grooves T8 and T9, per the manual. Small Arms Defense Journal says early uppers were machined from extrusions and later ones forged. Owners say Mod 0 uppers have a shorter ejection port.

No feed we read sells a stripped KAC upper or the deflector, so the PSA PA10 is a budget stand in, and we haven't confirmed it fits a KAC lower.

Barrel: 20 inch Mk11 profile, 1 in 11 twist, by Obermeyer

The manual gives 20 inches, five grooves and a right hand 1 in 11 twist, and Obermeyer made it, per SADJ and Small Arms Review. Lutz said KAC threaded the Mk11 barrel for the Army's flash suppressor. That points to a plain Mod 0 muzzle.

The enthusiast list treats the Mk11 and ER profiles as one, though whether they match is still an open question. If you want the true profile, owners name barrels from Rainier Arms, Nefarious Arms, HTX Concepts and Craddock, none of them in our feeds.

The Criterion barrel is an equivalent: it matches the length, 1 in 11 twist and rifle gas length, but it isn't sold as a Mk11 profile. The Ballistic Advantage is the budget pick at 1 in 10.

Gas block: KAC Mk11 block with suppressor slots

This block defines the Mk11: a top rail for the front sight, two vertical slots at 3 and 9 o'clock for the can's latch and an alignment pin at 6 o'clock. Gas runs through an M16A2 rifle length tube.

The enthusiast list calls it the KAC Double Picatinny, a name we found nowhere else. Owners buy surplus originals from Thoroughbred Armament kits or reproductions from Nefarious Arms.

The gas tube is exact. The railed block is a budget lookalike without slots, so nothing we carry takes the Mk11 can, and you should confirm your barrel's gas journal is .750 first.

Bolt carrier group and charging handle: KAC SR-25

The manual shows a KAC SR-25 carrier with a captive firing pin retaining pin, and most Mod 0 bolts use a single zigzag gas ring. Owners specify a carrier without sand cuts.

Both are budget .308 carriers, and we haven't confirmed either fits a KAC receiver. The manual says the M110's gas deflecting charging handle interchanges with the standard Mk11 handle. Our charging handle guide covers SR-25 pattern fit.

The LBE is a standard equivalent, and the LMT ambi handle stands in for the KAC ambi handle one owner lists as PN 30538.

Handguard: KAC Mk11 FF RAS rail, P/N 98513

The rail is KAC's free floating Rail Adapter System, P/N 98513. SADJ gives its length as 11.35 inches, and it has a front cutout for the gas block and 11 rib panels. It's discontinued, so you'll find originals only as surplus.

The KAC 11 rib panel is exact but out of stock. The Centurion is a budget quad rail Centurion lists for DPMS high profile uppers, and we haven't confirmed it fits a KAC receiver.

Front sight: folding Mk11 sight on the gas block rail

The Mod 0's backup front sight is a separate folding sight clamped to the gas block rail. The enthusiast list calls it a push button sight, but that lock is documented only on the later URX sight.

KAC's folding M4 sight is an out of stock equivalent, and the YHM is the budget pick. We haven't checked either one's height against the 600 meter rear.

Rear sight: KAC 600 meter flip up, P/N 98474

KAC's 600 meter flip up rear sight clamps in rail groove T3, per the manual. Lutz called it the standard Mk11 rear, adjustable from 200 to 600 meters.

The first card is the exact 98474, out of stock on 27 September. KAC's Micro 600 is the in stock stand in, if you can live with its smaller body.

Mk11 scope, rings, night sight and laser

The manual issued one scope, and owners report several that came later.

Optic: Leupold 3.5-10x with the M118LR cam

The manual lists a Leupold 3.5 to 10 power scope with an M3 type single turn cam for M118LR, 1 MOA elevation clicks and a mil-dot reticle. A forum member with ties to KAC says the first 100 Navy scopes were a commercial target model, and we can't verify that.

The enthusiast list and owners call it a Mark 4 3.5-10x40, and that scope is discontinued. If you want to stay with Leupold, the Mark 4HD 2.5-10x42 is the current equivalent with a mil reticle, and the Mark 3HD 3-9x40 is the budget pick.

Later scopes: Nightforce NXS and Schmidt and Bender

Owners date Nightforce NXS scopes on Mk11s to after Nightforce's July 2005 SOCOM contract, in 2.5-10x, 3.5-15x and 5.5-22x. Our hero photo from 2011 shows Nightforce rings, and the Mod 2 record lists Nightforce for the Navy.

The NXS cards carry current reticles, and the enthusiast list leaves out the 2.5-10x. One owner reports a Leupold Mark 5. Owners also report Schmidt and Bender PM II 4-16x42 scopes with Mk11 turrets, a contract item we can't card.

Scope mount: KAC two piece rings and the SIMRAD adapter

The Mod 0 used KAC's two piece 30mm rings. A Navy supplied SIMRAD adapter on the caps carried a military clip on night sight, and no civilian feed sells one.

The enthusiast list names a KAC one piece mount and a LaRue LT120 as equal options. The manual calls the one piece mount an M110 change, and we couldn't confirm the LT120.

KAC's rings aren't in any feed, so the Leupold Mark 4 rings are the equivalent, and the Warne Maxima QD rings are the budget pick.

Laser: AN/PEQ-2 and PEQ-15, added in the field

No laser appears in the Mod 0 system record. An owner's build lists an AN/PEQ-2, the enthusiast list adds the PEQ-15 and LA-5, and our 2011 hero photo shows an ATPIAL type box. We rate this slot weak.

Both are civilian stand ins, since the military lasers aren't sold to you. Our IR laser buyer's guide compares the DBAL with the issued ATPIAL line and budget options.

Mk11 suppressor, bipod and issued kit

The can makes a Mk11 a Mk11, and it's the hardest part to buy.

Suppressor: KAC Mk11 QD can, locked to the gas block

KAC's Mk11 QD can slides over the barrel and latches into the gas block slots, indexed by the 6 o'clock pin. The manual gives 12.25 inches (12.375 on another page), 1.86 lb and about 30 dB of reduction.

You won't find a muzzle device. Lutz said the Mod 0 never had a flash suppressor, and SEALs used the can to hide flash. The longer M110 can needs the M110 flash hider, so it won't fit a Mod 0.

Owners give the commercial can as KAC PN 98440 and say it's discontinued, and we don't stock it.

If your barrel is threaded, a 5/8-24 thread protector keeps the bare muzzle look.

Bipod: Harris S-LM on the KAC 98060 adapter

The manual lists a Harris LM Type S bipod with notched legs on a KAC adapter in groove B25. A kit list posted by the forum member with ties to KAC gives the adapter as P/N 98060. The enthusiast list names a BRM-S, a type the manual shows only with the Marines' Mod 2. It also spells KMW's Pod-Loc as KWM, and an owner saw Atlas bipods on one SEAL's kit.

The Harris S-LM is in stock with us. KAC's 98060 isn't in any feed and its current QD mount for Harris bipods was out of stock, so GG&G's rail adapter is a budget stand in.

M118LR ammunition, magazines, sling and case

The manual specifies 175 grain M118LR for combat and M852 for match, fed from KAC 20 round steel magazines.

The Winchester M118 LR is out of stock, so Federal's 175 grain Gold Medal is the in stock equivalent. Its 168 grain load is a match stand in, and we haven't matched it to M852.

Owners say factory KAC magazines are marked for law enforcement or government sale, so you'll want commercial SR-25 pattern magazines. KAC's own 20 round steel magazine was out of stock, and D&H, ASC and Magpul make in stock 20 round SR-25 pattern ones.

The manual also lists a QD sling stud and a leather sling.

The BCM mount is an equivalent with a push button socket, and the FAB is the budget pick. The U.S. Spec sling is military pattern leather, but we haven't checked it against the issued sling. The kit came in a 40 by 14 by 10 inch hard case with a Dewey rod. Owners call it a Pelican 1700, but Pelican's published size doesn't match, and we don't carry long cases yet.

Finish: factory black and SEAL field paint

The manual doesn't state a finish, but photos and surplus kits point to black anodized receivers and rail. SEAL rifles were often field painted tan and green, as a 2006 Small Arms Review photo and Navy photos from 2004 and 2011 show. The Marines wanted their Mod 1s black.

What you can buy today and what is unobtainable

Of the 29 slots, 25 had something in stock on GPP on 27 September 2026. Only five of those are the exact part.

Mk11 Mod 0 parts in stock on GPP today

Exact parts you can buy today cover the A2 stock, grip, trigger guard, gas tube and Harris S-LM bipod. Equivalents cover the Criterion 1 in 11 barrels, two stage triggers, the Leupold Mark 4HD and rings, and 175 grain match ammunition. The Nightforce NXS lines later rifles carried are in stock too.

Centurion Arms MK11 set: close, but not a Mod 0

The only product on GPP named MK11 is Centurion Arms' MK11 7.62 billet receiver set. Its lower has an integrated trigger guard, so it doesn't look like a Mod 0, and it was out of stock. We haven't carded it.

It still draws interest: 20 adds from 15 sessions between 31 January and 27 September 2026, and 19 Google impressions for its page from 29 June to 24 September. All eight Mk11 searches on GPP from 29 June to 27 September came from two sessions looking for this set.

Surplus only: the RAS, gas block, front sight and can

No feed we read sells the KAC FF RAS, the Mk11 gas block and front sight, the Obermeyer barrel, the Mk11 can, the Mod 0 marked lower or the SIMRAD night sight. You'll find the rail, block and sight only in surplus kits. Owners report very high prices for the can, and the PEQ lasers are military items.

What a Mk11 Mod 0 clone costs today

No KAC SR-25 rifle or 20 inch upper was in stock in our feeds on 27 September. So we priced the cheapest in stock stand in for each slot.

That total buys parts, not a proven rifle: we haven't confirmed they fit each other or a KAC receiver. The closer matches (LMT MARS-H, Geissele SSA, a Criterion barrel, the Leupold Mark 4HD and Mark 4 rings) bring you to $3,704.46.

Neither total covers the can, bipod, magazines, lower parts kit or ammunition.

How to build a Mk11 clone: convert an SR-25 or use parts

Owners either convert a KAC SR-25 or build from parts. Either way you'll need a surplus FF RAS and Mk11 front sight.

Nobody on GPP has saved one by name: none of the named carts saved from 10 December 2025 to 27 September 2026 names the Mk11. Of 110 carts created 16 December 2025 to 23 September 2026 that hold a KAC SR-25 lower, the Centurion set or a KAC SR-25 A2 upper, 30 have five or more items and a 7.62 class upper.

None holds a Leupold, a Criterion M118 barrel, a quad rail or a bipod, and three carry KAC's M110 can, the one that won't fit a Mod 0.

Our usual real build filter rejects carts mixing AR-10 and AR-15 tagged parts, as nearly every AR-10 build does, so we used the five item rule. It can't tell you whether anyone wanted a Mk11.

The KAC lower drew 83 adds from 42 sessions between 31 January and 27 September 2026, at a $1,528.31 median. In that window the Criterion barrels, Mark 4HD, NXS scopes and Mark 4 rings drew none.

Converting a KAC SR-25 ER upper to Mk11 spec

Owners convert a KAC SR-25 ER by fitting the Mk11 FF RAS and front sight, or they cut and reprofile a 24 inch SR-25 match barrel. They say the ER takes the Mk11 can, though nobody has shown its barrel matches the Mk11's.

We don't list the ER. KAC's SR-25 A2 upper and rifle are the nearest we carry, both out of stock, and their rail and gas block won't match a Mod 0.

A parts build on a KAC or LMT MWS lower

Start with a KAC SR-25 or LMT MWS lower, the A2 furniture and a two stage trigger that suits the KAC hammer. Add a Mk11 profile barrel, a surplus or reproduction gas block on a rifle length tube, the FF RAS and KAC sights. Every part in that list has a card above except the barrel, block, rail and front sight.

What the internet gets wrong about the Mk11 Mod 0

Here's what people call it, and what the records say.

The twist is 1 in 11, not the SR-25's 1 in 11.25

KAC's manual gives the Mod 0 a 1 in 11 twist. The 1 in 11.25 figure belongs to the original commercial 24 inch Remington barrels, per Sniper Central. If you see a barrel sold as Mk11 correct at 1 in 11.25, it follows the older SR-25 spec.

The Marines' 180 rifles were Mod 1s, not Mod 0s

The 180 rifle Marine buy became the black Mod 1. KAC put the order soon after September 2005, and Marine Corps Times dated the urgent need to 2007. Marine photos from July 2006 already call the MK-11 the Corps' newest sniper rifle.

Wikipedia says Marines began replacing Mk11 Mod 0s with the M110 in late 2011. Marine Corps Times had the M110 scheduled to replace the M39 EMR and the Mod 1 from January 2011, and its fall 2011 swap applied to the M39.

Mk11 Mod 0 weight: 10.44 pounds bare, not 15.3

Wikipedia and Small Arms Defense Journal give 15.3 lb and 45.4 inches without saying what that includes. KAC's manual gives 10.44 lb bare, 13.7 lb with scope, SIMRAD adapter and bipod, and 39.5 inches without the can.

SOCOM did not retire every Mk11 by 2017

Wikipedia says the Mk11 was completely replaced by 2017, citing a Kit Up post. That post reports a USASOC planning slide: divest Mk11s and Mk12s from late fiscal 2011, then field the Mk17 SCAR Heavy and Mk20 SSR through the third quarter of 2017.

A slide doesn't prove the swap happened, and Navy captions still said Mk-11 in 2026. For the SCAR, see our Mk17 Mod 0 clone build.

The civilian legal path to a Mk11 Mod 0 clone

The rifle needs no NFA paperwork. The can is the only NFA item.

A 20 inch semi auto rifle needs no NFA paperwork

The issued Mk11 fired semi auto only, so you've got no select fire parts to replace. Its 20 inch barrel clears the federal 16 inch minimum, and there's no muzzle device to pin and weld. Cut the barrel under 16 inches, though, and you've made a short barreled rifle, which some states ban.

Buying a Mk11 can: state law and registration checks

ATF announced on October 9, 2026 that it would stop enforcing Form 4 and Form 1 approval for suppressors, though it still accepts both at $0, and some states ban cans or only allow registered ones. Our guides to NFA paperwork in 2026 and what changed for suppressors cover the forms and the tax.

Owners describe some Mk11 cans for sale as NSW or DOD returns, so confirm the can is commercially registered and transferable before you pay. Before that change, owners reported Form 4 waits of about five months to a year.

State law: suppressor bans, rifle lists and magazines

Some states ban suppressors, and some restrict rifles by name or feature. One California owner reports the SR-25 is banned there by name. We haven't verified that, so check your state's list, and buy commercial SR-25 pattern magazines within your state's capacity limit.

Sources and photo credits

Every fact above comes from these sources.

Reference photos: what each one really shows

Plenty of photos captioned MK-11 don't show a Mod 0.