FAXON DUTY SERIES GUNNER PROFILE 10.5" PISTOL-LENGTH .458 SOCOM AR15 BARREL

Rifle Barrels › Duty Series › .458 SOCOM / .450 Bushmaster › 10.5″ Gunner, Pistol-Length  |  Works with: .458/.450 BCG • .875″ gas block • pistol-length gas tube • 11/16x24 muzzle devices

Why a 10.5″ .458 SOCOM

.458 SOCOM was designed after Mogadishu for exactly this: a big-bore round in a short M4 that puts a .458″ bullet on target from a gun that fits in a truck, with a rebated-rim case that fits a 5.56 magazine and runs on a standard lower. The cartridge burns out early, so the length costs little. A 300 gr load gives up about 150 fps to the 16″, from roughly 1,900 to 1,750 fps, and still carries more energy than a .44 Magnum carbine to 150 yards; 500 to 600 gr subsonics leave at the same 1,000 fps from either barrel, so the suppressed gun loses nothing at all. That is why the 10.5″ is the .458 that most people who shoot the cartridge suppressed end up with: a pistol or SBR that is as quiet as a .300 Blackout with a 600 gr bullet, and a hog and deer gun inside 150 yards with 300 gr supers. If straight-wall rules apply where you hunt, the .450 Bushmaster is the cartridge; the 16″ .458 SOCOM is the rifle version with a little more velocity and no paperwork.

A .458 bore takes most of the steel out of a 1″ blank, so this Gunner is built heavier than the 300 Blackout pistol barrels: a .980″ chamber journal, a straight .875″ body behind the gas block instead of a Government taper, an .875″ gas journal, and a straight .825″ section ahead of it that gives a suppressor mount a full shoulder to torque against. The body is where the barrel gets its stiffness and where the wall around the chamber and port has to be; on a 10.5″ there is not enough barrel ahead of the block to taper, so it stays at .825″ and the barrel weighs 1.50 lb. A pistol-length gas system with a .099″ port runs the low-pressure cartridge with a standard buffer, and the 11/16x24 muzzle takes Faxon’s MuzzLok .450/.458 brake or a .458-rated can. Give it an adjustable block from the start if it will run both supers and subs, because the two make very different gas.

What “Duty Series” Means

Duty Series is Faxon’s 4150 CMV line: the M4/M16 barrel alloy, salt-bath QPQ nitrided inside and out. 4150 carries about 0.50% carbon plus vanadium, which gives it more strength and wear resistance at temperature than 4140, and nitride adds a hard, corrosion-resistant surface to the bore and exterior without plating anything, and it adds virtually nothing to the surface: a few ten-thousandths of an inch, roughly a tenth the width of a human hair. It is the right combination for a barrel that will be shot hard, carried in the weather, and cleaned when there is time. Faxon’s stainless Match Series is the option when you want the precision-barrel formula; the Duty Series is the one to reach for when the rifle has a job.

What’s in the Box

How It’s Made

Every Duty Series barrel is made start to finish in Faxon’s Greater Cincinnati plant, on Faxon’s machines, to Faxon’s prints. This is the routing for this barrel.

1. Drill and pull-ream 4150 CMV bar is gun-drilled, then pull-reamed from the chamber end to a .451″ bore held to ±.001″, with a 32 Ra maximum finish checked on a profilometer and a borescope pass for reamer marks.
2. Button rifle A carbide button is pulled through from the chamber end to form six grooves, right-hand, one turn in 14 inches, to a .458″ groove diameter. Bore and groove are air-gauged.
3. Stress relieve and qualify The rifled blank is stress relieved before it becomes a finished barrel, then the OD is qualified true to the bore so every later cut references the same axis.
4. Turn the Gunner profile Muzzle end first: the .875″ gas journal is turned to .8740–.8750″ and checked with a micrometer on every barrel, held within .005″ of the bore, the .825″ forward section is turned true to the same axis, and the 11/16x24 muzzle is threaded and crowned. Then the breech end: the .875″ body, the .980″ chamber journal, and the extension thread.
5. Chamber The .458 SOCOM chamber is cut and checked with a headspace gauge; chamber surfaces are held to a 20 Ra finish.
6. MPI and nitride The machined barrel is 100% wet magnetic-particle inspected for surface and near-surface flaws, then salt-bath QPQ nitrided inside the bore and out, hardening the surface while adding virtually nothing to it.
7. Gas port, extension, pin After nitride, the .099″ gas port is drilled and reamed through the .875″ journal, the Big Bore M4 extension is torqued to 150 ft-lb and pinned, and the barrel is headspaced with a .458 SOCOM go/no-go gauge.
8. Mark The Faxon shield and order number are laser-engraved on the chamber journal and “.458 SOCOM 1-14T” ahead of the gas block.

What Reviewers and Owners Say

Voted Favorite Aftermarket Barrel by Shooting Sports Retailer every year since 2022 — the Gold Award, the top honor in the category. Faxon also took the Tactical Retailer Gold Award in the same category in 2025. Here is what independent testers and buyers have said about Faxon barrels and this one.

The 10.5″ is the newer of the two .458 SOCOM Gunners and has no reviews on FaxonFirearms.com yet; the 16″ it shares its prints with is rated 5.0 across 2 reviews here and 5.0 across 3 at OpticsPlanet, and the 10.5″ is carried at OpticsPlanet, Brownells, and AT3 Tactical.

Build It Out: Faxon Parts That Fit This Barrel

Everything below is made or specified to the same prints this barrel is, so the gas system, extension, and muzzle line up the first time. Pick one from each row and the upper is done.

Duty Series 10.5″ Gunner .458 SOCOM FAQs

What bolt, upper, and magazines does a .458 SOCOM barrel need?

The chamber is cut to the .458 SOCOM specification and headspaced with a .458 SOCOM go/no-go gauge after the extension is installed. The cartridge was designed around the AR-15 with a rebated .473″ rim, so it fits a standard lower and uses a bolt with a .308-size face: Faxon’s .458 SOCOM / .450 Bushmaster bolt and bolt carrier group have the .125″ bolt-face depth the cartridge calls for, and a 5.56 bolt will not work. The upper receiver has to match it: Faxon requires its Enhanced Forged Big Bore upper for every .458 SOCOM and .450 Bushmaster barrel, because its feed ramps and ejection port are opened up for the .541″ case and a standard 5.56 upper will not feed and eject it reliably. Magazines are the easy part: .458 SOCOM was designed to single-stack in an unmodified 5.56 magazine, so a 30-round 5.56 magazine holds about ten rounds; anti-tilt followers and magazines built for the cartridge feed most reliably. This barrel’s Big Bore extension has its feed ramps opened up for the case and ships headspaced. So the build is barrel, Big Bore upper, bolt, and magazines.

Why pistol-length gas on a 10.5″ .458 SOCOM, and what does it need to run?

Because a 10.5″ barrel is too short for a carbine port to have any dwell behind it, and .458 SOCOM is a low-pressure, fast-burning cartridge that needs its port early anyway: pistol-length puts it about 4.6″ from the breech with 5.9″ of barrel past it, and Faxon reams it to .099″, a little smaller than the .109″ on the 16″ because the shorter barrel sees higher pressure at the port. With factory 250 to 300 gr supersonic ammunition it cycles with a standard carbine buffer and spring and a .458 SOCOM bolt carrier group. Heavy subsonics (500 to 600 gr) make far less gas, so a gun that runs them, especially suppressed, wants an adjustable block and often a lighter buffer to cycle both. This barrel needs a pistol-length gas tube.

What is the Gunner profile, and why is the 10.5″ .458 SOCOM built with a straight body?

Faxon’s hybrid contour: full diameter where the barrel gets its stiffness (the chamber journal and the body behind the gas block) and lighter ahead of the block where mass only adds weight. Because a .458″ bore leaves very little wall in a 1″ blank, the .458 SOCOM Gunner runs a straight .875″ body and an .875″ gas journal where the 5.56 Gunner runs a Government taper and a .625″ journal, and on the 10.5″ the short section ahead of the block stays a straight .825″ with a full .850″ shoulder for a muzzle device or suppressor mount. That is why it weighs 1.50 lb at 10.5″, and why it takes the .875″ low-profile block instead of the .750″.

Why 1:14 twist, and what bullets does it stabilize?

Because .458 SOCOM runs everything from 250 gr supersonics to 600 gr subsonics, and the long, heavy subsonic bullets need more spin than the 1:16 or 1:18 a .45-caliber hunting load would. Faxon rifles it 1:14 so the same barrel stabilizes 250 to 300 gr hunting loads at 1,900 to 2,100 fps and 500 to 600 gr subsonics at 1,000, which is the whole point of the cartridge: a rifle that hunts with supers and shoots quiet with a can. From a 16″ barrel a 300 gr load leaves at about 1,900 fps with roughly 2,400 ft-lb, which is .45-70 territory.

What gas block and gas tube does it take?

A .875″ gas block on the 1.9″ journal and a pistol-length gas tube. Faxon makes a .875″ adjustable and a .875″ fixed low-profile block, and a 304 stainless pistol-length gas tube. The gas port is reamed to .099″.

What does 4150 CMV mean?

Chrome-moly-vanadium steel with about 0.50% carbon, the alloy the M4 and M16 barrel specification calls for. The higher carbon and the vanadium give it more strength and wear resistance at temperature than 4140, which matters most on a barrel that will see fast strings and sustained fire.

Is the nitride inside the bore?

Yes. Salt-bath QPQ nitride is a diffusion treatment, not a plating, so it hardens the surface of the bore and the exterior while adding virtually nothing to it: the surface grows by a few ten-thousandths of an inch, .0002–.0004″, roughly a tenth the width of a human hair or about the diameter of a single red blood cell. It also gives the barrel its corrosion resistance and matte black finish.

Does it come with a gas block, gas tube, or muzzle device?

No. It ships with the black-oxide Big Bore M4 extension installed, torqued, pinned, and headspaced. Gas block, gas tube, and muzzle device are sold separately; the muzzle is threaded 11/16x24.

Will it work with a suppressor?

Yes. The 11/16x24 muzzle takes a .458-rated (.45-70 or .458 SOCOM rated) can on an 11/16x24 mount, never a .30-cal, .36-cal, or pistol-only .45 can, and a .458 SOCOM that switches between supers and heavy subsonics, especially with a can, needs an adjustable block to run both, and the can has to be rated for the cartridge. For a gun that runs suppressed most of the time, pair it with the Faxon .875″ adjustable gas block so you can bring the gas down.

Can I put a 10.5″ barrel on my AR?

A barrel under 16″ makes the firearm either a pistol or a short-barreled rifle under federal law. Build it on a lower that has only ever been a pistol, or on a lower registered as an SBR with an approved Form 1 or Form 4, and check your state law before you buy. A 10.5″ cannot be pinned to 16″ with a normal muzzle device; that is what the 16″ is for. Faxon cannot advise on your specific configuration.

How fast does .458 SOCOM leave a 10.5″ barrel, and what about subsonics?

About 1,950 fps with 250 gr loads and 1,750 with 300 gr, depending on the load, or roughly 2,000 ft-lb at the muzzle, about 150 fps behind the 16″. Subsonic loads with 500 to 600 gr bullets leave at the same 1,000 fps they do from a 16″, with 1,100 to 1,300 ft-lb, which is why the short barrel is the natural home for a suppressed .458: it gives up nothing with subs and only a little with supers.

Is .458 SOCOM legal in straight-wall states, and how far will a 10.5″ hunt?

Usually not, and that is the one thing to know before choosing it over .450 Bushmaster. The .458 SOCOM case has a slight shoulder, so most states with straight-wall rules (Ohio, Michigan’s southern zone, Iowa, Indiana) do not allow it for deer; check your regulations, and if you hunt in one of those states, build the .450 Bushmaster instead. Everywhere a bottleneck rifle cartridge is legal, a 10.5″ .458 is a 150-yard deer and hog gun with 300 gr supers, and the deer and hog laws for pistols and SBRs vary by state as well.

10.5″ or 16″ .458 SOCOM?

The 10.5″ if the gun will wear a suppressor and shoot subsonics: it gives up nothing with 500 to 600 gr subs, only about 150 fps with 300 gr supers, and with a can on it is the length of a bare 16″ rifle. The 16″ if you want a rifle with no paperwork, the last 150 fps for hunting at 200 yards, or a barrel that runs supers on a standard block with more margin. Both take the same Big Bore upper, bolt, gas block, and 11/16x24 devices.

Is the gas journal dimpled for set screws?

No. The journal ships round so any .875″ low-profile, clamp-on, or pinned gas block fits the 1.9″ journal. A set-screw block holds on the nitrided journal when its screws are torqued with thread locker; if you want dimples, mark them through the block’s screw holes and drill.

Where is it made, and what is the warranty?

Made in Greater Cincinnati, Ohio, from bar stock to finished barrel, and covered by the Faxon Lifetime Guarantee.

Dimensions are from the Faxon engineering print and inspection sheets for this SKU; weight is nominal. Gas block, gas tube, and muzzle device sold separately. Owner reviews are quoted as written from FaxonFirearms.com product reviews; press quotes link to their sources. Award: Shooting Sports Retailer Choice Awards, Favorite Aftermarket Barrel, Gold. Covered by the Faxon Lifetime Guarantee.