FAXON DUTY SERIES HBAR PROFILE 16" MID-LENGTH 5.56 NATO AR15 BARREL

Rifle Barrels › Duty Series › 5.56 NATO / .223 › 16″ HBAR, Mid-Length  |  Works with: 5.56 BCG • .750″ gas block • mid-length gas tube • 1/2x28 muzzle devices • 5.56 suppressors

Why the HBAR Profile

Barrel steel does two jobs under fire: it stays stiff so the muzzle points where it did on the last shot, and it soaks up heat so the bore does not walk as a string goes on. Both scale with diameter, and the HBAR is the profile that refuses to give any of it back. Behind the gas block it runs a straight .800″ body, where the SOCOM runs a Government taper down to .610″ and the Gunner tapers the same way and then thins further ahead of the block; ahead of the block it keeps the SOCOM’s full .730″. The result is the stiffest 16″ 5.56 barrel in the Duty Series, with the most thermal mass, which is what you want when the barrel will be hot for most of its life: a rifle used to teach, a rifle shot in drills all afternoon, a suppressed rifle that traps heat at the muzzle, or a 5.56 you want to shoot small groups from a bench with. Mid-length gas puts the port 9.66″ from the breech with six inches of dwell, so it cycles softly on a standard buffer and stays civil with a can.

At 2.06 lb it weighs about five ounces more than the 16″ SOCOM and eleven more than the 16″ Gunner in the same length and gas system. That is the price of the extra steel, and it is worth paying for a rifle that lives on a range and not for one that lives on a sling. The HBAR is also the profile the A2-era heavy-barrel carbines and the classic 16″ HBAR rifles were built with, so it is the right barrel for a build that wants that look and heft. If you want most of the heat capacity for less weight, the SOCOM keeps the .730″ forward section and tapers the rest; if weight and balance come first, the Gunner is the carbine barrel Faxon is known for.

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 .2195″ 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 8 inches, to a .2250″ 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 HBAR profile Muzzle end first: the .750″ gas journal is turned to .7490–.7497″ and checked with a micrometer on every barrel, held within .005″ of the bore, the .730″ forward section is turned true to the same axis, and the 1/2x28 muzzle is threaded and crowned. Then the breech end: the .800″ body, the .980″ chamber journal, and the extension thread.
5. Chamber The 5.56 NATO 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 .081″ gas port is drilled and reamed through the .750″ journal, the M4 extension is torqued to 150 ft-lb and pinned, and the barrel is headspaced with a 5.56 go/no-go gauge.
8. Mark The Faxon shield and order number are laser-engraved on the chamber journal and “5.56 NATO 1-8T” 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 HBAR is the newest 16″ 5.56 profile in the Duty Series and has no reviews on FaxonFirearms.com yet; the 16″ SOCOM it shares its steel, rifling, gas system, and forward section with is rated 5.0 across 25 reviews here, Faxon’s 5.56 heavy-profile barrels average 4.8 across 48 reviews at OpticsPlanet, and the Duty Series 5.56 line holds 4.7 across 25 at MidwayUSA.

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 16″ HBAR 5.56 FAQs

Is this a 5.56 NATO or .223 Remington chamber?

5.56 NATO, headspaced with a 5.56 go/no-go gauge after the extension is installed. A 5.56 chamber has the longer throat that lets it fire both 5.56 NATO and .223 Remington safely; the reverse is not true, so a .223-chambered barrel should not be fed 5.56.

Why mid-length gas on a 16″ barrel?

Because it puts the port about two inches farther from the chamber than carbine-length gas, so the system taps the bore at lower pressure. On a 16″ barrel that means a softer, more linear recoil impulse, less wear on the bolt and buffer, and better manners with a suppressor. Mid-length is the right gas system for a 16″ 5.56, and this barrel needs a mid-length gas tube.

What is the HBAR profile, and how does it compare to SOCOM and Gunner?

HBAR stands for heavy barrel, and Faxon’s version is exactly that: a .980″ chamber journal, a 6° taper to a straight .800″ body that runs all the way to the gas block, a .750″ gas journal, and a full .730″ section ahead of it to the muzzle. The SOCOM keeps the same .730″ ahead of the block but runs a Government taper behind it; the Gunner tapers behind the block and thins to .500″ ahead of it. HBAR is the stiffest of the three and carries the most heat, at 2.06 lb against 1.73 for the SOCOM and 1.37 for the Gunner. It takes the same .750″ low-profile block as the SOCOM, on a 1.1″ journal.

What bullet weights does the 1:8 twist stabilize?

Everything from 55 gr FMJ through 69 and 77 gr match bullets. 1:8 is the most versatile twist for a general-purpose 5.56; 1:7 is only needed for the longest tracer and 80-plus grain projectiles, and 1:9 starts to run out of spin above 69 gr.

What gas block and gas tube does it take?

A .750″ gas block on the 1.1″ journal and a mid-length gas tube. Faxon makes a .750″ adjustable and a .750″ fixed low-profile block, and a 304 stainless mid-length gas tube. The gas port is reamed to .081″.

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 M4 extension installed, torqued, pinned, and headspaced. Gas block, gas tube, and muzzle device are sold separately; the muzzle is threaded 1/2x28.

Will it work with a suppressor?

Yes. The 1/2x28 muzzle takes any 5.56 direct-thread can or mount, and mid-length gas is the friendlier system for suppressed use. For a rifle that runs suppressed most of the time, pair it with the Faxon .750″ adjustable gas block so you can bring the gas down.

What gas block fits the 1.1″ journal?

Any .750″ low-profile block that is 1″ long or shorter, which covers Faxon’s adjustable and fixed .750″ blocks and most low-profile blocks on the market. The journal is short because the HBAR steps straight from the .800″ body to the .750″ journal and back up to .730″, so a block longer than the journal will hang over the shoulder and not seat. The journal ships round for set-screw, clamp-on, or pinned blocks; if you want dimples, mark them through the block’s screw holes and drill.

Is the HBAR more accurate than the SOCOM or Gunner?

Cold, no: all three are the same 4150 blank, the same button rifling, the same chamber, and the same air-gauged bore, and a cold 16″ Faxon of any profile shoots about the same. Hot is where the HBAR earns its weight. With more steel around the bore it heats slower, flexes less, and holds its point of impact through longer strings, so the group you shoot on the third magazine looks like the one you shot on the first. If the rifle will be shot in long strings, taught with, or run suppressed for hours, the HBAR is the profile that stays put; if it will be carried and shot in short strings, the lighter profiles give up nothing.

Who is the HBAR for?

Anyone whose barrel spends most of its life hot: instructors and students, range rifles that go through cases of ammunition, suppressed rifles that trap heat at the muzzle, and shooters who want to bench a 5.56 and see what it will do. It is also the right profile for a clone or retro build that calls for the classic heavy barrel. It is not the barrel for a lightweight carbine; that is what the Gunner is for.

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.