Second of Ten LLC // Stuart, Florida // Short-Barreled Rifle

12″ SOTM5 8.6 BLACKOUT RECCE SBR, SNIPER GREY CERAKOTE®

A large-frame rifle specified one part at a time.

$2,700.00 SKU RFL-M5-86BLK-B120-SG

12 inch SOTM5 8.6 Blackout RECCE SBR in Sniper Grey Cerakote, right side

This SOTM5 is a 12″ 8.6 Blackout short-barreled rifle built on Second of Ten’s billet SOTM5 receivers: a thermal-fitted MOD-0 upper over a 7075-T6 aluminum lower. It is gassed to run both supersonic and subsonic 8.6 Blackout, and the barrel, gas system, bolt, recoil parts and controls are each chosen for that job and named below. Receivers and handguard are two-tone: Sniper Grey Cerakote® with a black Cerakote® top Picatinny rail.

A note on the name

SOTM5 names the rifle; the serialized part is the lower receiver. MOD-0 names the billet upper fitted to it, here in its no-forward-assist configuration. RECCE is Second of Ten’s word for the short, light reconnaissance configuration; the stock is Reptilia’s RECC·E™ Carbine Stock, and RECC·E™ is Reptilia’s mark.

//The Barrel

The barrel is the part of this rifle that most decides how it shoots, so it is the part chosen first. Second of Ten fits the Faxon Duty Series 12″ 8.6 Blackout barrel in the Gunner profile, and these are the features of it that matter.

4150 CMV, QPQ nitrideChrome-moly-vanadium barrel steel, salt-bath QPQ nitrided on the bore and exterior, with no plating.
1:3 twist, 5-groove button riflingThe fast twist 8.6 Blackout is designed around, stabilizing heavy subsonic bullets. Bore and groove are air-gauged to ±.001″.
Cut to the 8.6 BLK drawingChambered to the 8.6 Blackout cartridge drawing and headspaced 100% with an 8.6 BLK go/no-go gauge.
Inspected before nitriding100% wet magnetic particle inspected; bore finish 32 Ra maximum, checked on a profilometer, with a borescope pass and a target crown.
Torqued and pinned extensionDPMS Gen 1 pattern .308 barrel extension, torqued to 150 ft-lb and pinned by Faxon.
Pistol-length gasA .078″ port, reamed to size, 4.78″ from the breech face, on a .875″ journal held within .005″ of the bore. Faxon lists the barrel at 2.0 lb.
Adjustable for supersonic and subsonicA Superlative Arms .875″ solid adjustable gas block, bleed-off type with 30 locked positions, set so the rifle runs both supersonic and subsonic 8.6 Blackout. It is fitted with set screws secured with Rocksett®.
M18×1.5 thread, Q Cherry Bomb XLA Q Cherry Bomb XL 8.6 mm brake is installed on the M18×1.5 thread: 17-4 stainless, 360° ports so it needs no timing or shims, fast-attach for Q’s PORQ CHOP and SHORT CHOP silencers.

//The Handguard

A free-float handguard only helps if it stays where it was put. The 9.8″ SOT Wedge-Lock M-LOK® handguard is built around that.

Steel HD barrel nutA heat-treated steel heavy-duty barrel nut, phosphate finished, carries the handguard.
Tri-lug clamp, not a pressure clampHeat-treated billet lugs pull the handguard against the barrel nut, secured with Grade 8 hardware.
Full-length top Picatinny railAn unbroken top rail, full length, finished in black Cerakote® to match the receiver’s rail.
Seven sides of M-LOK®M-LOK® slots on all seven sides of the handguard.
6061-T6 aluminum, 9.6 oz1.45″ inside diameter. Two-tone: Sniper Grey Cerakote® body, black Cerakote® top rail.
Free floatNothing on the handguard bears on the barrel ahead of the barrel nut.

//The Case

01

The barrel comes first

12″ Faxon Duty Series 8.6 Blackout barrel in the Gunner profile: 4150 CMV, QPQ nitrided, 1:3 twist, pistol-length gas. The rest of the rifle is specified around it; the detail is set out above.

02

A thermal-fitted billet upper

The SOTM5 MOD-0 upper is machined from 7075-T6 aluminum billet to the LR-308 DPMS high pattern, with laser-engraved T-marks and a dry film lubed interior. It is thermal fitted to the Faxon barrel, so the joint between barrel and receiver is an interference fit and not a slip fit.

03

No forward assist, by design

This rifle uses the no-forward-assist configuration of the MOD-0, with the forward assist bore closed by a threaded forward assist pin.

04

One rifle, both kinds of 8.6

8.6 Blackout is loaded both supersonic and subsonic, and a fixed gas port suits only one of them. The Superlative Arms bleed-off block lets the rifle be set to run both, and to run cleaner suppressed, because excess gas is vented at the block rather than driven into the action.

05

A superfinished bolt carrier group

Faxon Superfinished AR10 BCG, Gen 2, nitride, rated for .308 Win, 6.5 Creedmoor and 8.6 Blackout: MIL-SPEC 8620 carrier, superfinished and QPQ nitrided; 9310 bolt, shot peened and MPI tested; S7 extractor with nested .308 springs and O-ring; 4140 cam pin; heat-treated 4140 gas key on Grade 8 fasteners, fully staked.

06

Caliber marked inside and out

The ejection port dust cover is engraved with the caliber on both the interior and the exterior. The marking reads whether the cover is open or closed.

07

A buffer that takes energy out

A KynSHOT RB5005 hydraulic buffer with a Tubb Precision flatwire rifle-length spring. Every other buffer moves energy around inside the rifle; a hydraulic damper converts some of it to heat. KYNTEC builds it in 17-4 stainless, rated −30°F to +150°F, for AR-10 and A5-length tubes, and the claim with real weight behind it is reduced bolt bounce.

08

A two-stage trigger, left as made

LaRue Tactical MBT-2S two-stage trigger with a straight bow. It breaks crisply at 4.5 lb (2.5 lb first stage, 2.0 lb second) with a smooth and positive reset. An additional heavy trigger spring that raises the pull to 6 lb is included. Second of Ten does not stone, polish or alter sear engagement surfaces.

09

Controls on both sides

Ambidextrous bolt release, with a paddle-style oversized bolt catch on the left and Second of Ten’s own serrated release button on the right. Extended left-side magazine catch release with a right-side button. Breek Arms WARHAMMER Mod2 AR-10 charging handle with oversize latches on both sides.

10

A selector you can set to 45° or 90°

The Radian Weapons Talon® 45/90 ambidextrous safety selector runs as a standard 90° selector or as a 45° short throw by rotating the shaft 180° inside the lower. It is installed and configured at 90° and can be reconfigured by the end user.

11

Tension where the halves meet

The billet lower carries an upper receiver tension screw, a threaded bolt catch pin and a rear takedown detent spring with set screw, with Battle Arms Development enhanced AR-308 steel pivot and takedown pins.

12

A stock that keeps its cheek weld

Reptilia RECC·E™ Carbine Stock for SR-25 / A5 / AR-10, with its own SR-25/A5-length 7075-T6 receiver extension: length of pull 12.375″ to 15″ with a constant cheek weld, switchable QD points, 12.8 oz with the tube. Paired with a Reptilia CQG™-L grip.

//Inspect It Yourself

This rifle has a zoomable inspection page showing both sides of the rifle as built, so the markings and machining can be read from the photograph instead of taken from a spec table. The serial number is blurred; no other marking is altered.

Open the viewer → SOT_SOTM5-12-86BLK-RECCE_SG_SBR_Zoom_Viewer.html · SOT-WEB-RFL-031
Right sideLeft sideZOOM 5×

//Specifications

Model
SOTM5 · 12″ RECCE short-barreled rifle
SKU
RFL-M5-86BLK-B120-SG
Chambering
8.6 Blackout
Overall length
31″ collapsed · 33.5″ extended
Weight
7 lb 13.8 oz
Barrel
12″ Faxon Duty Series, Gunner profile · 1:3 right-hand twist · 5-groove button rifled · 2.0 lb
Barrel steel and finish
4150 CMV · salt-bath QPQ nitride, bore and exterior · wet magnetic particle inspected
Chamber
8.6 Blackout, cut to the cartridge drawing · headspace 100% checked with a go/no-go gauge (Faxon)
Barrel extension
DPMS Gen 1 pattern .308 · torqued to 150 ft-lb and pinned by Faxon
Muzzle
Threaded M18×1.5 · target crown · Q Cherry Bomb XL 8.6 mm brake, 17-4 stainless, 360° ports
Gas system
Pistol length · .078″ port · .875″ journal · Superlative Arms .875″ solid adjustable bleed-off gas block, 30 positions · set screws secured with Rocksett®
Handguard
9.8″ SOT Wedge-Lock, M-LOK®, free float · Sniper Grey Cerakote®, black Cerakote® top rail
Handguard construction
6061-T6 aluminum · 1.45″ inside diameter · tri-lug clamp · full-length top Picatinny rail · M-LOK® on seven sides · steel HD barrel nut · Grade 8 hardware · 9.6 oz
Upper receiver
SOTM5 MOD-0 billet, no forward assist · 7075-T6 aluminum · LR-308 DPMS high pattern · threaded forward assist pin · laser-engraved T-marks · dry film lubed · thermal fitted · Sniper Grey Cerakote®, black Cerakote® top rail
Charging handle
Breek Arms WARHAMMER Mod2, AR-10 / LR-308 · black · oversize ambidextrous latches
Dust cover
Caliber engraved, interior and exterior
Bolt carrier group
Faxon Superfinished AR10, Gen 2, nitride · DPMS Gen 1 pattern · 8620 carrier, superfinished · fully staked 4140 gas key on Grade 8 fasteners
Bolt
9310 steel, shot peened, MPI tested · S7 extractor, nested .308 springs and O-ring · 4140 cam pin
Lower receiver
SOTM5 billet, marked MULTI · 7075-T6 aluminum · Type III hard anodized · Sniper Grey Cerakote® · upper receiver tension screw
Lower details
Threaded bolt catch pin · rear takedown detent spring with set screw · Mil-Spec buffer retainer
Trigger
LaRue Tactical MBT-2S, two-stage, straight bow · 4.5 lb (2.5 lb first stage, 2.0 lb second) · 6 lb heavy spring included
Safety selector
Radian Weapons Talon® 45/90, ambidextrous · configured at 90°
Takedown and pivot pins
Battle Arms Development enhanced AR-308 pin set · steel
Bolt release, left
Paddle-style oversized bolt catch
Bolt release, right
SOT proprietary, serrated
Magazine release
Ambidextrous · extended left-side release · right-side button
Receiver extension
Reptilia SR-25/A5 length, 7075-T6 · supplied with the stock
Buffer
KynSHOT RB5005 hydraulic, 17-4 stainless
Buffer spring
Tubb Precision flatwire, rifle length
Stock
Reptilia RECC·E™ Carbine Stock for SR-25 / A5 / AR-10 · black · LOP 12.375″–15″
Grip
Reptilia CQG™-L (CQG™ Grip – Long) · black
Magazine
Magpul PMAG® 20 LR/SR GEN M3™, plain and unmarked, included · magazines shown in photographs may differ
Options
Magpul MBUS 3 front & rear flip-up sights, black (MAG1166-MAG1167), +$75.00 · Lancer Systems Gen 2 L7AWM® 20-round magazine, Translucent Dark Earth or Translucent Smoke, in place of the standard magazine, +$20.00
Finish
Two-tone: Sniper Grey Cerakote® receivers and handguard, black Cerakote® top rail
Classification
Short-barreled rifle (barrel under 16″) · see the notice below
Price
$2,700.00

//Notices

Short-barreled rifle: check your state

Since ATF’s open letter of 9 October 2026, federal NFA registration is not enforced for short-barreled rifles, and this rifle transfers through your FFL on a Form 4473 with a NICS check. State and local law still decide whether you can own one, an ATF Form 20 is still required before taking an SBR across state lines, and the federal policy could change. Confirm with your local FFL before ordering. This is not legal advice.

Set the gas for the load

The adjustable gas block should be set for the ammunition in use, supersonic or subsonic, and reset when a suppressor is fitted or removed. A setting that suits one load is not necessarily right for another.

The selector is set at 90°

The Talon® 45/90 selector ships configured as a standard 90° selector. It can be changed to a 45° short throw by rotating the shaft 180° inside the lower receiver.

Bombproof by Design™Precision // Purpose // Performance
SOT-RFL-SS-010 · Version 1.1 · 4 NOV 2026Second of Ten LLC · FFL 07 / SOT 02 · CAGE 9X6K6 · UEI JHTMQKEVAUK5