A Compact Match Series Faxon Barrel for 300 Blackout AR-15 Builds
The Faxon Match Series 15B35P7NGQ-5R-NP3 is a 7.5 inch Gunner profile .300 Blackout barrel for compatible AR-15 builds. It is built for the shooter who wants a compact 300 BLK barrel with a fast 1:5 twist, pistol-length gas, 5R rifling, 416-R stainless steel construction, salt bath nitride / QPQ finish, an NP3-coated M4 barrel extension, and 5/8x24 muzzle threads.
This is not a 16 inch rifle barrel and it is not the standard Duty Series 4150 CMV version. It is a Match Series barrel for a lawful AR pistol, properly registered SBR, or other legal host configuration where compact length, heavy subsonic bullet stability, suppressor use, and careful system tuning matter.
Why Choose the 7.5 Inch 1:5 Twist Faxon?
The reason to choose this barrel is the combination of compact 7.5 inch length and fast 1:5 twist. A faster twist rate is especially relevant in short 300 Blackout builds where longer, heavier subsonic bullets and suppressors are common. The buyer looking at this barrel is usually not trying to build a plain range carbine; he is trying to build a compact 300 BLK upper around a specific role.
The 7.5 inch length gives the builder a short package before adding a suppressor, muzzle device, or blast-forward device. Compared with a 6 inch barrel, it gives a little more barrel length and system margin. Compared with a 10.5 inch barrel, it keeps the upper shorter and more specialized.
Match Series Construction
This is a Faxon Match Series barrel, not a standard Duty Series barrel. It uses 416-R stainless steel, 5R button 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 salt bath nitride / QPQ 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.
7.5 Inch vs. 6 Inch vs. 10.5 Inch 300 Blackout
The 7.5 inch barrel is the middle short-barrel option between the ultra-compact 6 inch Match Series barrel and the more forgiving 10.5 inch compact barrel. It makes sense when the buyer wants a shorter build than a 10.5 inch upper, but does not want to go all the way down to the most specialized 6 inch configuration.
For a general-purpose compact 300 BLK upper, the 10.5 inch barrel may be the easier starting point. For the shortest possible Match Series build, the 6 inch 1:5 twist barrel may be the answer. This 7.5 inch Match Series barrel is the compact middle ground: short, fast-twist, suppressor-friendly, and still built around a practical Gunner profile.
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 becomes more important as barrels get shorter. 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 7.5 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 deliberate about ammunition selection. 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 7.5 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 7.5 Inch 300 BLK Barrel?
This is a strong choice for the AR-15 builder who intentionally wants a 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, heavy-subsonic 300 BLK projects, and specialty uppers where short overall length is a major 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 7.5 inch length, fast 1:5 twist, Gunner profile balance, 416-R stainless construction, 5R rifling, NP3 barrel extension, salt bath nitride / QPQ finish, pistol-length gas, and 5/8x24 muzzle threads.
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