FAXON MATCH-X SERIES GUNNER PROFILE 7.5" 1:5T PISTOL-LENGTH 300 BLK AR15 BARREL

What “Honed & Lapped” Actually Means

A barrel bore starts as a drilled and reamed hole. Reaming leaves a surface finish around 32 Ra, which is good enough for a duty barrel and is where most stainless match barrels stop before the rifling button goes through. On a MATCH-X barrel the reamed bore is honed to 8 Ra, a fourfold improvement, before it is button rifled. The point of honing first is the button: it forms the lands and grooves by displacing steel rather than cutting it, and it can only produce a surface as clean as the one it starts from. A profilometer checks the honed finish and a borescope checks for tool marks before the barrel moves on.

Rifling roughens that surface again, and so does everything that follows. The button cold-works the bore at very high pressure, raising the grain along every land edge; the 1150°F stress relief lets the steel relax and leaves a thin surface oxide; and contouring and chambering release more stress and move the bore by a few ten-thousandths. So after all of that machining is done, the bore is lapped back to 16 Ra, polishing lands and grooves together so the bullet sees one uniform surface from throat to crown. For scale, 16 Ra is the finish class of a ground crankshaft journal or a hydraulic valve spool, and it is smoother than the brushed stainless on a refrigerator door, which runs 25 to 40 Ra.

Why it matters: the smoother the bore, the less copper and carbon it holds, the more uniform the friction on every bullet, and the more consistent the velocity from shot to shot. That shows up as tighter vertical dispersion at distance, a shorter break-in, and a barrel that cleans in a fraction of the passes. Faxon then button-rifles the honed bore with 5R geometry, five lands with sloped sides instead of the sharp corners of conventional rifling, which deforms the jacket less and fouls less again.

The other MATCH-X difference is the outside. Match Series barrels are nitrided; MATCH-X barrels are left as bare 416-R stainless, blasted with S110 media for a uniform matte finish. The bore is plugged and the extension, muzzle threads, and gas port are masked during blasting, so the media only ever touches the exterior. Nothing is added to the steel, so nothing can affect the bore, and the matte stainless surface is thermally stable and easy to keep clean. The trade is that bare stainless wants a wipe of oil after wet or humid use, the same as any stainless match barrel.

What’s Included

How It’s Built and Inspected

1. 416-R stainless bar is gun-drilled and pull-reamed from the chamber end, then honed to 8 Ra. Bore diameter is checked with go/no-go pins, finish with a profilometer, and the surface with a borescope.

2. The bore is button-rifled with a 5R, 1:5 right-hand twist (.3015″ bore, .3085–.3105″ groove), then stress relieved at 1150°F for a minimum of four hours. Bore and groove diameters are air-gauged at three points along the length.

3. The blank is chopped, re-centered, and profiled between centers: Gunner contour, .750″ gas journal held to .0007″, 5/8x24 muzzle threads, the three caliber-ID rings, and the recessed crown.

4. The 300 Blackout chamber is cut with a go gauge in the machine, verified on a CMM, and borescoped for an even lead. The rifled, chambered bore is then lapped to a 16 Ra finish, bringing lands and grooves to one uniform surface from throat to crown. Every barrel is magnetic-particle inspected.

5. The nickel-Teflon M4 extension is torqued to 150 ft-lb, the gas port is drilled and reamed to .104″, the extension is pinned, and headspace is checked with a 300 BLK go/no-go gauge. Finally the exterior is blasted with S110 media for the uniform matte finish, with the barrel plugged and the extension, muzzle threads, and gas port masked so the media never touches a sealing or bearing surface.

300 Blackout From a 7.5″ Barrel, By the Numbers

300 Blackout was designed to do two things a 5.56 cannot: burn its full powder charge in a very short barrel, and shoot heavy subsonic bullets quietly through a suppressor from a standard AR-15 bolt and magazine. A 7.5″ barrel is the length the cartridge was built around. Subsonic loads lose almost nothing here; a 190 gr Sub-X that Hornady rates at 1,050 fps from a 16″ barrel still leaves a 7.5″ at roughly 1,000 to 1,030 fps, comfortably above the 900 fps floor Hornady specifies for Sub-X expansion. Supersonic 110 gr loads run about 2,050 fps from this length against 2,375 from a 16″, which is still a 200-yard rifle. The 1:5 twist is what lets one barrel do both: it fully stabilizes 220 and 240 gr subsonic solids that a 1:8 leaves marginal, and it does not hurt a 110 gr supersonic at the velocities a 7.5″ produces.

MATCH-X 7.5″ Gunner 300 Blackout FAQs

What is the difference between MATCH-X and Match Series?

Both are 416-R stainless with 5R button rifling, a nickel-Teflon extension, and a recessed target crown. MATCH-X adds a bore that is honed to an 8 Ra finish before rifling and brush-lapped to 16 Ra after machining, and leaves the exterior as uncoated, S110-blasted stainless instead of nitride. Match Series is the nitrided, harder-wearing choice; MATCH-X is the smoother-bore, maximum-consistency choice.

How is this different from Faxon's best-selling 7.5″ 300 BLK barrel?

It is the same barrel with a different finish. The Match Series 7.5″ Gunner 1:5 300 BLK (15B35P7NGQ-5R-NP3) has been Faxon's best-selling barrel since 2025: 416-R, 5R 1:5, Gunner profile, pistol gas, nitrided inside and out. This MATCH-X version takes that exact design, hones the bore to 8 Ra before rifling, laps it back to 16 Ra after machining, and leaves the exterior as bare S110-blasted stainless. Same twist, same profile, same gas port, same extension. Choose the Match Series if you want nitride's wear and corrosion resistance; choose MATCH-X if you want the smoothest possible bore for a barrel that will spend its life behind a suppressor.

Why a 1:5 twist for 300 Blackout?

Because subsonic bullets are long, slow, and heavy, and stability comes from spin. At 1,050 fps a 220 gr bullet in a 1:8 barrel is only marginally stable, and the 240 gr and heavier monolithic solids that have become popular for suppressed hunting are not stable at all; some makers label them 1:5 only. One turn in five inches spins every subsonic bullet made, lead-core or solid, to full stability from a 7.5″ barrel. It still shoots 110 to 125 gr supersonics; at the 2,000 to 2,100 fps a 7.5″ produces, jacketed bullets are well inside their limits.

What are the three rings behind the muzzle threads?

They are a caliber mark. A 300 Blackout barrel uses the same bolt, magazines, and upper as 5.56, and a 300 BLK round will chamber in a 5.56 barrel with catastrophic results, so Faxon machines three rings behind the muzzle threads on its 300 BLK barrels to make the caliber obvious at a glance. Three rings means 300 Blackout. Mark your magazines and uppers the same way.

Do I need an adjustable gas block, and which one?

Yes, and the Faxon .750″ adjustable gas block. The .104″ port on this barrel is sized to cycle subsonics unsuppressed, which is the most gas a 300 BLK ever needs; the moment you add a suppressor or switch to supersonics, that same port over-gasses the rifle, throws brass, and puts extra blowback in your face. The adjustable block's 14 detented settings let you dial the port to each combination, and because it meters at the gas block rather than with a screw in the gas path, it does not carbon up. Set it once for your can and load and leave it.

Which Faxon suppressor pairs with this barrel?

Any of Faxon's .30 cal cans, mounted on a HUB-compatible 5/8x24 mount. The HARMONIX ION is titanium and under 8 ounces, the lightest option for a barrel this short; the HARMONIX Sentry is Haynes 282 superalloy and full-auto rated for hard use; CORESYNC has a removable 3D-printed core that you can clean, which matters on a subsonic gun that fouls quickly. All three are low-backpressure designs, which keeps a pistol-gas 300 BLK from over-gassing and keeps the ejection port clean.

What is the Gunner profile, and what does it weigh?

0.89 pounds. The Gunner keeps a full .845″ diameter from the chamber to the gas block, where pressure and heat live, then steps to the .750″ journal and a .730″ forward section. It carries a suppressor without the muzzle flex of a pencil barrel and without the weight of a Government contour, which is why every 300 BLK barrel Faxon sells is a Gunner.

Will 300 BLK cycle reliably from a 7.5″ barrel?

Yes, with the right setup. The pistol-length gas system on this barrel is designed for the cartridge's fast-burning powders, and the .104″ port cycles subsonic loads unsuppressed with a standard carrier and buffer. Suppressed, subsonics cycle easily; supersonics cycle hard unless the gas block is turned down, which is the reason for the adjustable block. Run a standard carbine buffer and spring to start, use magazines built for 300 BLK if you shoot heavy subsonics, and tune from there.

Do I need to break in a honed and lapped barrel, and how do I care for it?

Less break-in than a conventional barrel; the honed and lapped 16 Ra bore has already smoothed the tool marks that break-in normally shoots out. Clean after the first range session, then shoot it. Because the exterior is uncoated 416-R stainless, wipe it with a lightly oiled cloth after wet or humid use and run an oiled patch through the bore before storage; suppressed subsonic shooting is dirty, so clean the bore and chamber more often than you would on a 5.56.

Is the barrel extension installed and headspaced?

Yes. The nickel-Teflon M4 extension is torqued to 150 ft-lb, pinned, and the assembly is checked with a 300 BLK go/no-go gauge before it ships. Install it in a mil-spec upper with a standard barrel nut and a standard 5.56 bolt; no additional headspacing is required, though checking headspace with your own bolt is always good practice.

Faxon Lifetime Guarantee. Covers manufacturing and material defects to the original purchaser. Excludes damage from misuse, neglect, improper installation, non-standard ammunition, or modifications. Bore erosion and finish wear from normal use are not defects. Register your product at faxonfirearms.com/product-registration to expedite service. Full terms: faxonfirearms.com/warranty-privacy-terms.

Dimensions and tolerances are nominal from Faxon engineering drawings. Gas block, gas tube, barrel nut, and muzzle device not included. Barrels are firearm components; verify function and headspace with your bolt before firing, and confirm reliable cycling with your ammunition and gas block setting. Teflon® is a registered trademark of The Chemours Company FC, LLC.

For questions, contact customerservice@faxonfirearms.com.