LVAW clone build: the SIG MCX Low Visibility Assault Weapon

In the spring of 2014, SIG Sauer handed gun writers a short, suppressed 300 Blackout carbine. Military Times called it the MCX "Black Mamba." That summer, DefenseReview gave it a longer name: MCX LVAW, for Low Visibility Assault Weapon.

SIG never sold the rifle owners later pieced together from photos, most of them tied to Delta Force. We rebuilt it slot by slot and priced every part in our feeds on 27 September 2026, so you'll see what matches and what nobody can sell you.

What an LVAW clone copies: SIG's suppressed 6.75 inch MCX

An LVAW clone copies a SIG MCX with a 6.75 inch 300 BLK barrel and a can that hides under the rail. DefenseReview spelled out the acronym in 2014; no official document we found confirms it.

SIG's own page calls the MCX LVAW a 6.75 inch 300BLK design and a replacement for sub gun style platforms. Owners describe prototype receivers, a proprietary 10.5 inch rail over the back of the can, and SIG MIL-SRD762 direct thread cans.

Game wikis and airsoft rails share the name. You're reading about the real rifle.

LVAW history: a requirement before a rifle

LVAW first named a special operations requirement, and SIG's MCX answered it. Military Times reported in April 2014 that the MCX started life as a rifle caliber replacement for the suppressed HK MP5SD. For SOCOM's 5.56 answer to close quarters work, you'll want our Mk18 Mod 0, the earlier SOCOM CQB carbine.

A U.S. Marine Corps officer fires a 9mm Heckler & Koch MP5SD during a foreign military small arms course at Yuma, Arizona, on 4 December 2003. SIG pitched the MCX as a rifle caliber replacement for this gun. Photo: Lance Cpl. Keith Underwood, U.S. Marine Corps. Public domain, via Wikimedia Commons.

The LVAW requirement and AAC's Honey Badger

SIG announced on 17 February 2014 that AAC founder Kevin Brittingham was joining. He said his former engineering chief, Ethan Lessard, "did the LVAW (honey badger)," tying the name to AAC's gun before the MCX went public.

Guns & Ammo later called the MCX the Honey Badger's competitor for the LVAW contract within SOCOM, and The Firearm Blog says the MCX grew out of the LVAW program. Whether that was one competition or a run of unit tests isn't public.

Who carried the LVAW: Delta and other JSOC units

Most photos and owner accounts tie the LVAW to Delta Force, the Army's Combat Applications Group. Sandboxx reported in 2022 that DEVGRU had been seen with it and that Gen. Austin Scott Miller's bodyguards were seen carrying it in Afghanistan.

The Miller photos are tied to his 2018 to 2021 command but circulate without dates or credits. We found no DEVGRU photo, and UK use rests on one forum poster and one blog photo.

See also our CAG HK416 clone build and the Delta MRE clone build.

LVAW variants over its service life

The fielded rifle differs from SIG's 2014 demo guns, and SOCOM's later SIG buys often get mixed up with it.

SIG's 2014 demo guns vs fielded rifles

The 2014 reports disagree. DefenseReview's demo gun had a thumb operated gas setting for subsonic and supersonic ammo, a slim folding stock and a can on what it called tapered threads. DefenseReview clocked it at 927 rounds per minute on full auto.

Military Times said its demo gun cycled 110 and 220 grain bullets with no complicated switching mechanism. Nobody knows if fielded rifles kept a switch, though Space Magic says the original rail reads Subsonic and Supersonic.

One 2024 forum post puts an 8 inch rail on prototypes and 10.5 inches on contract guns.

SURG and RSAR: SOCOM's later SIG buys

Neither is an LVAW. In July 2018 SOCOM gave SIG a $48 million, five year IDIQ for SURG, an integrally suppressed 5.56 upper for the M4A1 lowers in our M4A1 URGI clone build.

In May 2022 SOCOM announced its intent to buy MCX Rattlers in 5.56 and 300 BLK with SIG SL series cans as a Commercial PDW. The 15 September 2022 award, a five year IDIQ valued at $5 million, named the program the Reduced Signature Assault Rifle, or RSAR.

How to build an LVAW clone: start with an MCX host

Every LVAW clone starts as a commercial SIG MCX, because no LVAW receiver was ever sold and a select fire lower is a machine gun. Your job is picking the semi auto MCX that gets closest, and ours is the SIG MCX Rattler LT 300 BLK 6.75 inch pistol.

Legacy, Virtus, Spear LT or Rattler LT

One enthusiast parts list names the Legacy, SIG's first generation MCX, as the closest match. The AR15.COM build list accepts any commercial lower without the ambi bolt catch.

None of our feeds sells a Legacy upper or lower alone. The replica rail comes in Legacy, Virtus and Spear LT, and Rattler versions, so you can build on any of them.

Rattler LT 6.75 inch 300 BLK: right barrel out of the box

SIG's Rattler LT pistol in 300 BLK comes with the 6.75 inch barrel and a Pivoting Contour Brace. It was $2,499.99 with two offers in stock on 27 September 2026. It's an equivalent host that fills your receiver, barrel, piston and carrier rows.

SIG says its standalone 6.75 inch Rattler LT upper "offers the same design" as the LVAW, but it showed out of stock at $1,799.99 and isn't in our feeds. The Rattler itself came from separate requests and launched with a 5.5 inch barrel. Its LT receivers have ambidextrous controls.

A 7th Special Forces Group (Airborne) soldier fires a SIG Sauer MCX Rattler LT during a stress shoot at Eglin Air Force Base, Florida, on 31 July 2026. It's one of SIG's current short MCX models, not an LVAW. Photo: Staff Sgt. Joshua Taeckens, U.S. Army (VIRIN 260731-A-JF826-1045). Public domain, via DVIDS.

SIG MCX-LTAW: the 2026 factory homage

In September 2026 SIG listed three MCX-LTAW models as coming soon: a pistol, an SBR and a suppressed SBR combo. All get a 6.75 inch 300 BLK barrel and ambidextrous controls, and both SBRs carry a folding KM stock.

The combo adds an SQX direct thread can and a ROMEO4T-PRO, and SIG says it was "inspired by the LVAW concept." TFB reported anticipated prices of $2,700 and $3,700. SIG hadn't confirmed a date or price by 27 September 2026. Its rail and ambidextrous controls differ from the LVAW's.

LVAW parts list: the issued part and what to buy

Here's the whole rifle on one screen, in the slot order of the enthusiast parts list we cross checked against owner accounts and SIG's copy.

Product photography is supplied by the listed merchants through their affiliate feeds.

Exact means we list the issued part. Equivalent means we list a civilian stand in. Hunt means you'll find it sold direct or used, outside our feeds.

The lower receiver group

The trigger guard slot reads N/A on the enthusiast list because the MCX lower includes it.

Lower receiver: the prototype MCX and its controls

Owners describe a prototype lower SIG never sold, with a different magwell and no ambidextrous controls apart from the charging handle. The Mag Life says the controls are ambidextrous. We trust the owner photos more.

The forum fits non ambi safeties and magazine catches from SIG 516, 716 or M400 rifles, which we don't stock. Otherwise your semi auto Rattler LT is the lower.

Stocks: the Kate Moss thin folding stock

Owners name two stocks as most common: SIG's thin skeleton folding stock, nicknamed the Kate Moss for its thin profile, and SIG's folding and telescoping stock. Some guns wore a PDW stock.

SIG's Thin Folding Stock 2.0 lists at $249.99 and Parker Mountain Machine's KM style stock at $160 without a hinge, both outside our feeds. Skip the Sig 8901412 in our catalog, a Folding Visor Stock. Any stock on a 6.75 inch barrel makes your gun an SBR.

Our cards are SIG's original thin folding stock, not in stock on 27 September, and the folding and telescoping stock in FDE, which was.

Trigger and grip: Gen 1 MCX, semi auto only

The issued group was SIG's Gen 1 safe, semi and auto group. Auto parts are machine gun parts, so you keep your MCX's semi auto group, the stand in the enthusiast list and the AR15.COM list both name.

The TriggerTech below is an upgrade, not a clone part. SIG hasn't published the Gen 1 grip's part number, so owners hunt them used; Reptilia's CQG is an AR-15 grip, which the MCX lower takes, and a budget stand in.

The upper receiver group

Your Rattler LT fills most of the upper. The charging handle is the one part to replace.

Upper receiver: prototype MCX, Legacy as the stand in

Owners describe the issued upper as a heavier SIG prototype. Tabs on the genuine handguard index into it, the opposite of the Legacy and Virtus. So a genuine rail won't fit a commercial upper, and each replica comes in a version per generation.

The enthusiast list calls the Legacy upper the closest match, but we don't list one alone, so your Rattler LT's upper stands in.

Barrel: SIG 6.75 inch 300 BLK

The barrel is the best documented part: SIG's copy, Sandboxx and The Mag Life all give 6.75 inches in 300 BLK. Owners say its profile is slightly thinner than SIG's commercial Legacy barrel.

SIG hasn't published a twist rate, and the figures online trace to tabletop game notes, so we don't print one.

Why there is no gas block or muzzle device

The MCX runs a short stroke piston with dual recoil springs and no buffer tube, so there's no separate gas block. Issued guns show no flash hider either, because the can threads straight on.

DefenseReview's tapered threads were probably a tapered shoulder on standard 5/8x24, like SIG's SRD762. SIG never published the issued thread; the replicas use 5/8x24, so pull the flash hider off your Rattler LT.

BCG and charging handle: Gen 1 MCX, short latches

Owners describe an LVAW marked Gen 1 carrier nearly identical to the commercial Legacy one, so your Rattler LT's carrier fills the slot. SIG recalled some first generation carriers. Check any used Legacy you buy.

Owners say the Gen 1 ambidextrous handle with short latches came only on early Legacy guns. Our two SIG small latch listings name no platform and had no offer in stock, so the card is Radian's Raptor for the MCX, a stand in.

The LVAW handguard: issued rail vs replicas

The rail makes an MCX read as an LVAW, and no retailer in our feeds can sell you one.

Handguard: Space Magic x Shadow Strategic LVAW rail

The issued rail is proprietary and 10.5 inches long, and Sandboxx says it covers part of the can. The Mag Life says it's neither M-LOK nor KeyMod, and Space Magic describes an aluminum original with a steel link, engraved Subsonic and Supersonic.

The joint Space Magic Industries and Shadow Strategic replica comes in Legacy, Virtus and Spear LT, and Rattler versions at $649.99. On 27 September 2026 only Space Magic had stock.

Check Space Magic's fitment chart before you order, because it warns 6.75 inch Rattler LT owners off the Rattler version. Shadow Strategic sells matching rail sections for $72.50.

Lancer carbon and other stand in handguards

Lancer's 8 inch carbon MCX rail shows up on some issued guns, far less often than the LVAW rail. We list it in 10.5, 12 and 18 inches; the card is the 10.5, which UN12's owner clone used.

Midwest Industries' 10 inch Rattler rail covers a can for less, though its Rattler LT fit is unconfirmed. Both are M-LOK, so you'll add Magpul's sections.

Sights, optics, light and laser

Most of the aiming kit is still on sale, so your clone gets closest here. The laser is the exception.

Iron sights: KAC Micro 600 m rear and Micro front

Owners and the enthusiast list agree on Knight's Armament folding Micro sights with the 600 meter rear, though early rifles wore unidentified SIG flip ups. You can get the KAC rear today, but no feed had the front in stock on 27 September 2026. The SIG flip up set is only a stand in for an early rifle, since nobody has named the exact SIG model.

Optic and mount: Aimpoint T-2, EOTech or ROMEO4T

The issued optic is an Aimpoint Micro T-1 or T-2, and the T-1 is discontinued, so you'll buy the T-2. The Mag Life also spots an EOTech XPS3 and a SIG ROMEO4T in photos, and one poster calls the ROMEO4T the unit's most common now.

Owners and the enthusiast list name LaRue LT660 and LT751, Aimpoint LRP and Geissele mounts on mostly FDE Wilcox .410 inch risers. We don't list the LaRue or Wilcox parts. The G33 and a Wilcox BOSS-E it doesn't explain come from the enthusiast list alone. Our Sicario task force build runs a similar mix.

Light: SureFire Scout on a short 1913 section

The Mag Life and owners say Scout lights seem to be the unit's choice. The AR15.COM list calls a tan M600C very common. The M600C is discontinued, so pick another tan Scout: the M600DF card had no offer in stock, but the Scout Pro stand in did.

The issued mount was a short 1913 section or a unit made mount. Space Magic sells a CAG style replica, $25 on sale on 27 September 2026, and the enthusiast list names SIG and RailScales mounts.

Laser: LA-5 or NGAL, and civilian IR stand ins

The issued lasers are L3's LA-5 and L3Harris' NGAL, with PEQ-15s mentioned too. All of them are military and agency only, so you'll need a civilian stand in like the DBAL-A3 or LS321G below. Our Zero Dark Thirty HK416 build goes further into lasers and night vision.

LVAW suppressor: MIL-SRD762 cans and replicas

The can is the other signature part, and two common claims about it are wrong.

Suppressor: SIG MIL-SRD762-16 and Ti-10

Owners name two issued cans, the stainless MIL-SRD762-16 at about 32 to 33 oz and the titanium MIL-SRD762Ti-10, both direct thread. They say the -16 was never sold commercially, while commercial Ti-10s were and are discontinued.

The commercial SRD762Ti-16 is a common stand in that owners say was never issued. The enthusiast list adds a plain MIL-SRD762-Ti we can't place, and SIG publishes no specs for any MIL can.

Replica cans and commercial stand ins

Tyr1 Outfitters and Space Magic sell two replicas at $1,199 each, both 5/8x24 direct thread. The steel ST-16 is 8.9 inches and 33 oz. The titanium Ti-10 is 6.9 inches and 14 oz.

You'll buy them direct. The cards are commercial cans the forum names as alternatives, not lookalikes, and every can here is an NFA item. Our best 300 Blackout suppressors guide has more.

Magazines, sling and 300 BLK ammo

Owners and the enthusiast list name a black Okay Industries Gen 1 Surefeed 30 round magazine engraved 300BLK, and photos show 40 round PMAGs too, which the enthusiast list says wore a TTI base extension. Shadow Strategic sells a Surefeed approximation and engraving direct. Our card is TTI's PMAG 40 with its base pad fitted, and the 30 round PMAG MOE is a budget stand in.

No single sling was issued. Any good two point sling you own is period correct, and owners list VTAC, Vickers/BFG and Spiritus. Our card is a black Vickers, with the Magpul MS1 as a budget stand in.

Subsonic or supersonic: which 300 BLK to run

Run both. The Mag Life says operators switch loads by swapping magazines, and no issued load is documented. UN12's clone owner zeroed his for supersonic, so confirm where your subsonic load hits before you trust that zero.

Our 300 Blackout vs 5.56 guide covers the cartridge choice.

The civilian legal path to an LVAW clone

An LVAW clone meets the NFA twice: a 6.75 inch barrel with a stock is a short barreled rifle, and the can is a suppressor.

A 6.75 inch barrel: SBR with a stock, pistol without

ATF announced on October 9, 2026 that it would stop enforcing NFA approval, registration and marking requirements for SBRs, though it still accepts a Form 1 or Form 4 at $0. Crossing state lines still needs ATF approval on Form 5320.20. Brownells lists SIG's factory Rattler LT SBR (RMCX-300B-6B-LT-SBR), but it was out of stock and isn't in our catalog.

As a pistol with a brace or no stock, your Rattler LT avoids SBR registration federally, but read our pistol brace rules first.

A 16 inch barrel avoids the SBR question but isn't an LVAW, and pinning and welding a can to 16 inches isn't practical from 6.75. Our 2026 NFA paperwork changes and barrel length and SBR rules guides cover the process.

Suppressors, select fire parts and state bans

Every can here, replicas included, is an NFA item, and ATF announced on October 9, 2026 that it would stop enforcing Form 1 and Form 4 approval for suppressors. Read what changed for suppressors before you buy.

Only registered pre 1986 select fire parts are legal for civilians, so you'll run the semi auto group. Some states ban SBRs or suppressors outright.

What you can buy today and what is unobtainable

We matched 25 slots against our catalog on 27 September 2026. Ten have the issued part listed, counting the empty muzzle slot and generic 300 BLK ammo. Eleven have a civilian stand in, and four have a budget stand in or nothing.

Sold direct in batches, not in stores

The rail, the replica cans, KM style stocks, LVAW rail sections and Wilcox risers come from small makers in timed batches, outside our feeds. If you want one, sign up for the maker's restock alerts.

Parts no retailer can sell you

Nobody sells the prototype receivers, the LVAW profile barrel, the marked carrier, the issued rail or, owners say, the steel MIL-SRD762-16. The LA-5, PEQ-15 and NGAL are military and agency only, and the M600C and T-1 are discontinued.

What an LVAW clone costs today

The core cost $5,271.98 on 27 September 2026: the Rattler LT host at $2,499.99, the rail at $649.99, a replica can at $1,199 and a T-2 at $923. A KAC rear, a tan Scout Pro and a DBAL-A3 take you to $7,458.18, before a stock, a front sight and the NFA paperwork.

TFB reported an anticipated $3,700 for SIG's LTAW combo, can and optic included. No cart our users named between 10 December 2025 and 27 September 2026 mentions the LVAW, MCX or Rattler. Three guest carts used the Rattler LT 6.75 host between 6 August and 12 September 2026, and three carts is an anecdote.

What the internet gets wrong about the LVAW

Most LVAW errors are 2014 press copy and forum posts repeated as fact. Here's the short list, then the four that matter most.

Hidden under the rail, not integrally suppressed

If you've read that the LVAW is integrally suppressed, that's TFB in September 2026 echoing Military Times in 2014. Owners describe detachable direct thread cans with their back half under the long rail, which makes them look integral.

The issued rail is not M-LOK

The issued rail takes 1913 sections on threaded holes and is neither M-LOK nor KeyMod, per The Mag Life. The M-LOK idea probably comes from popular clones on Lancer rails and ALTRD's BLK Widow.

Black Mamba was a 2014 demo name

Black Mamba appears in 2014 coverage of SIG's pre production demo gun, and no source shows a unit using it. A forum rumor, which TFB repeats, says it meant killing the Honey Badger's chances, on the idea that black mambas prey on honey badgers. TFB still calls the nickname purported.

The April 2015 contract date is forum rumor

The date traces to a forum post relayed on AR15.COM in 2020 that mixes rumor, Leigh Neville's book and notes for a tabletop game campaign. TFB repeats it only as what forum sources say, and we found no contract notice.

Sources and photo credits

Every fact above traces to one of these. Owner accounts carry the parts, trade press the dates.

Where to see real LVAW photos

We found no public domain LVAW photo on Wikimedia Commons or DVIDS. For real reference, the AR15.COM Official LVAW Photo and Discussion Thread has owner photos, including comparisons with commercial parts.