Description
Their capacity. Our architecture. One rifle. The Quattro-15 lower and the QMAG-53 magazine are developed and manufactured by Desert Tech. The pairing is ours: an HM Defense Monobloc® upper, thermal fitted to a SOTM4 MOD-0 forged receiver, built by the SOT Custom Shop on the Quattro-15 lower, a combination Desert Tech does not offer. Bombproof by Design™.
Open the zoom viewer: both sides of this rifle, photographed as built.
Barrel
- 16″ HM Defense Monobloc®, chrome-lined, 4150 chrome-moly steel (CrMo), Black Cerakote®
- Balanced barrel taper/profile
- 5.56×45mm NATO, .223 Remington compatible · 1:8 twist · 1/2×28 muzzle thread
- Mid-length gas, with the gas block milled straight into the barrel blank: no separate block to clamp, pin or shift
- A2 Extended Flash Hider, Black Cerakote®, standard
- Optional add-on: 4-port hardened flash hider, Black Cerakote®, $40.00
- Optional add-on: Faxon MuzzLok® Gunner 3-port 5.56 steel muzzle brake, $60.00
- Optional add-on: Faxon MuzzLok® stainless steel Plan B muzzle brake, $75.00
- Other choices on inquiry: we offer a wide variety, including mounts for many suppressor manufacturers and other Plan B options. Contact us
- Suppressor-ready with any of the Faxon MuzzLok® brakes: the MuzzLok® removes to leave the 1/2×28 thread for a direct-mount suppressor
- Configuration shown: optional 4-port hardened flash hider, Black Cerakote®. Ships with the standard Black Cerakote® A2 Extended Flash Hider.
Upper Receiver
- SOTM4 MOD-0 forged upper, 7075-T6, black anodized, barrel thermal fitted with no retaining compound and no bedding
- Forward assist, phosphate finish
- SOT Enhanced HMB™ bolt carrier group, Black Nitride (standard)
- Optional upgrade, in place of the standard group: Young Manufacturing M16 Chrome BCG with HMB™ bolt, $149.00, supplied as Young Manufacturing build it, without SOT’s enhancements: no arrow-indexed cam pin, no index-marked gas key, and the gas key is not staked
- Optional upgrade, in place of the standard group: Microbest Super-Stake C158 all-chrome BCG, heavy-duty stake, with chrome HMB™ bolt, $149.00
- Arrow-indexed cam pin on the standard SOT Enhanced group — always installed in the same direction for better wear and cam pin life
- Index-marked gas key on the standard SOT Enhanced group
- Laser-engraved caliber markings inside and outside the ejection port cover for rapid visual caliber confirmation
- Breek Arms WARHAMMER Mod2 ambidextrous charging handle
Handguard
- 15″ SOT Wedge-Lock M-LOK, black anodized, free float, full-length top Picatinny rail
- Twin-lug wedge lock to a steel barrel nut, with anti-rotation tabs
Lower Receiver
- Desert Tech Quattro-15, machined from a 7075-T6 aluminum forging, black Type III hard-coat anodized (rollmarked MULTI-CAL)
- Integrated trigger guard, forged into the lower
- Radian Talon ambidextrous safety selector, black
- Desert Tech proprietary ambidextrous bolt release and magazine release, standard on every Quattro-15
- Nitride pivot pins (SOT standard)
- Integrated QD sling socket on the left side of the receiver
- Upper receiver tensioning set screw (fit and feel, not accuracy)
- LaRue Tactical MBT-2S two-stage trigger, curved bow (standard) or straight bow: the only trigger offered on the Quattro-15 series
- Carbine-length buffer system with H2 buffer, the only recoil system offered on the Quattro-15 RECCE
Furniture
- Reptilia RECC·E™ Carbine stock, black
- Reptilia CQG™ grip, black
Extra Information
- Ships with one Desert Tech QMAG-53 (53-round quad stack)
- Ships in a 42″ black Plano SE rifle case: high-density molded polymer, high-density interlocking foam
- Includes the Desert Tech Quattro-15 Magwell Adapter Kit (P/N ACC0292), which lets the dedicated quad-stack Quattro-15 lower accept standard USGI and traditional AR-15 / STANAG pattern 30-round magazines
- Overall length 34″ with the stock collapsed, 37″ extended · weight 6 lb 11.5 oz unloaded
- Not available in California, Connecticut, Delaware, Illinois, Maryland, Massachusetts, New Jersey, New York, Rhode Island, Washington or Washington, D.C.
- Colorado and Vermont restrict the 53-round QMAG-53 but not the rifle: there, and wherever magazine-capacity limits apply, the rifle ships with compliant magazines instead, and the adapter is included regardless
- Laws change: please confirm with your local FFL before ordering
- Optional add-on: Magpul MBUS 3 front & rear flip-up sight set (MAG1166-MAG1167), black, $75.00: impact-resistant polymer, spring-loaded with an ambidextrous push-button, tool-less front elevation, rapid-select rear aperture, 0.44″ high folded, standard AR height deployed, Picatinny mount, made in the USA
- Title I rifle · ships to your FFL dealer only
MONOBLOC® and HMB™ are marks of HM Defense, LLC, used under license. Desert Tech, Quattro-15 and QMAG are marks of Desert Tech; RECC·E™ and CQG™ are marks of Reptilia. Their appearance indicates that Second of Ten incorporates the component, not sponsorship, affiliation or endorsement.









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