An Ultra-Compact Match Series Faxon Barrel for 300 Blackout Builds
The Faxon Match Series 15B35P6NGQ-5R-NP3 is a 6 inch Gunner profile .300 Blackout barrel for compatible AR-15 builds. It is built for the shooter who wants an extremely compact 300 BLK barrel with a fast 1:5 twist, pistol-length gas, 5R rifling, 416-R stainless steel construction, nitride finish inside and out, an NP3-coated M4 barrel extension, and 5/8x24 muzzle threads.
This is a specialized barrel, not a general-purpose 16 inch rifle barrel and not the more forgiving 10.5 inch compact option. The 6 inch length is for a lawful AR pistol, properly registered SBR, or other legal host configuration where very short overall length is the priority. Confirm the final firearm configuration before ordering or installing any sub-16 inch barrel.
Why Choose the 6 Inch 1:5 Twist Faxon?
The main reason to choose this barrel is the combination of extremely short length and fast 1:5 twist. A faster twist rate is especially relevant in short 300 Blackout builds where heavy subsonic bullets and suppressors are common. The buyer looking at this barrel is usually not trying to build a traditional carbine; he is trying to build a compact 300 BLK host around a specific role.
The 6 inch barrel length keeps the upper very short before adding a suppressor, muzzle device, or blast-forward device. That short length can be attractive for a compact suppressed host, but it also makes the overall system more sensitive to ammunition, suppressor backpressure, gas setup, buffer weight, spring choice, magazine geometry, and bolt carrier group selection.
Match Series Construction
This is a Faxon Match Series barrel, not the standard Duty Series 4150 CMV version. It uses 416-R stainless steel, 5R rifling, and an NP3-coated M4 barrel extension. For the buyer comparing Faxon 300 BLK barrels, those are the major reasons to step into this Match Series version instead of choosing one of the standard nitride 1:8 twist Gunner barrels.
The barrel is finished in nitride inside and out for surface protection and easier cleanup. The Gunner profile keeps the barrel light and handy while retaining the balance advantages that make Faxon's Gunner contour popular on compact AR builds.
6 Inch vs. 7.5 Inch vs. 10.5 Inch 300 Blackout
The 6 inch barrel is the most compact path in this group. Compared with a 7.5 inch or 10.5 inch barrel, it gives the builder a shorter package, but also less barrel length and less margin for a simple, forgiving setup. It should be chosen deliberately by a buyer who understands that ultra-short 300 Blackout builds may require more careful tuning.
For a general-purpose compact 300 BLK upper, the 10.5 inch barrel is often the easier starting point. For a shorter AR pistol or registered SBR with a balance of compactness and system margin, a 7.5 inch barrel may make sense. This 6 inch Match Series 1:5 barrel is the specialized option for the builder who is intentionally prioritizing minimum barrel length and fast twist.
Pistol-Length Gas and System Tuning
This barrel uses a pistol-length gas system with a .750 inch gas block journal. The builder needs a compatible .750 gas block, pistol-length gas tube, and handguard with enough internal clearance for the chosen gas block and muzzle setup.
300 Blackout function is system-dependent, and that is especially true in a 6 inch barrel. Supersonic and subsonic ammunition can behave very differently, and suppressor use changes gas pressure. The barrel is the foundation, but the final setup should be tested with the gas block, gas tube, bolt carrier group, buffer, recoil spring, magazine, muzzle device, suppressor, and ammunition actually being used.
Suppressed and Muzzle-Device Considerations
The 5/8x24 muzzle thread gives the builder access to common .30-caliber muzzle devices and suppressor mounts. A barrel this short is often chosen with suppressor use in mind, but thread pitch alone does not make a suppressor setup correct.
Before firing with a suppressor installed, confirm bore clearance, suppressor rating, cartridge compatibility, muzzle-device compatibility, shoulder support, thread engagement, torque method, and alignment. Also verify that the suppressor manufacturer approves use on a 6 inch .300 Blackout barrel with the intended ammunition. Short barrels can impose different limits than longer 300 BLK hosts.
1:5 Twist and Ammunition Selection
The 1:5 twist is aimed at stronger stabilization in short 300 Blackout barrels, especially with heavy subsonic bullets. That does not remove the need for testing. Bullet weight, bullet length, bullet construction, velocity, suppressor use, and the exact firearm setup all matter.
For this barrel, the buyer should be more deliberate about ammunition selection than with a standard 16 inch range rifle. Test the exact supersonic and subsonic loads you intend to use. Watch for reliable feeding, safe pressure signs, consistent cycling, stable bullet flight, suppressor compatibility, and proper function with the magazines and buffer system selected for the build.
300 Blackout Ammunition Discipline
300 Blackout should be treated as its own ammunition system. Because 300 BLK, 5.56 NATO, and .223 Remington are all commonly used in AR-15 platforms and magazines, owners should keep ammunition, magazines, rifles, and uppers clearly separated to avoid dangerous mix-ups.
Use only ammunition specifically marked .300 AAC Blackout, .300 Blackout, or 300 BLK in this barrel. Do not mix 300 BLK ammunition with 5.56 NATO or .223 Remington ammunition at the bench, in the range bag, or in loaded magazines.
Legal Configuration Note
This is a 6 inch barrel. It is not a 16 inch rifle barrel. Use it only with a lawful AR pistol, properly registered short-barreled rifle, or other legal host configuration. Installing a barrel under 16 inches on a rifle can create a short-barreled rifle subject to NFA regulation.
Confirm the final firearm configuration, receiver status, federal law, state law, and local restrictions before ordering or installing any sub-16 inch barrel.
Who Should Choose This Faxon Match Series 6 Inch 300 BLK Barrel?
This is a strong choice for the AR-15 builder who intentionally wants an ultra-compact 300 Blackout barrel with Match Series construction, 1:5 twist, 5R rifling, NP3 M4 extension, pistol-length gas, and 5/8x24 muzzle-device flexibility. It fits lawful AR pistol builds, registered SBRs, compact suppressed hosts, and specialty 300 BLK uppers where minimum barrel length is the main goal.
It is less suitable for a buyer who wants a 16 inch rifle barrel, the easier 10.5 inch general-purpose compact option, a standard 1:8 twist Duty Series barrel, a large-frame AR barrel, or a 5.56 / .223 Wylde upper. The value here is the specific combination of 6 inch length, fast 1:5 twist, Gunner profile balance, 416-R stainless construction, 5R rifling, NP3 barrel extension, nitride finish, pistol-length gas, and 5/8x24 muzzle threads.
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