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The AR-15 Mil-Spec A2 Birdcage W/Crush Washer 5.56 is the standard USGI flash hider designed for AR-15 / M4 / M16 rifles chambered in 5.56 NATO / .223 Remington with 1/2×28 threaded barrels, engineered to reduce visible muzzle flash and protect the muzzle crown. The A2 birdcage is the current US military standard muzzle device, replacing the earlier 3-prong and A1 birdcage, featuring a closed bottom to reduce dust signature when shooting prone and five evenly spaced slots on the top and sides that disrupt and cool expanding gases to reduce flash. When a rifle fires, high-temperature propellant gases exit the muzzle at high pressure and ignite upon contact with atmospheric oxygen, creating a bright fireball that reveals the shooter’s position in low light and disrupts night vision — the A2 birdcage’s slots break up that gas column into smaller, cooler jets that mix with air and cool before igniting, reducing flash to a small, dim spark rather than a large fireball. The closed bottom prevents gas from venting downward and kicking up dust, sand, and debris when shooting from the prone position or near the ground, which would obscure vision and reveal position. The A2 also serves as a sacrificial baffle that protects the precision muzzle crown from dings and impacts that would degrade accuracy.
This device is manufactured to mil-spec dimensions from 4140 carbon steel bar stock, with 1/2×28 TPI threads that match standard AR-15 5.56 barrels, and finished with black phosphate or black nitride that matches mil-spec barrel finishes and provides corrosion resistance. The package includes a standard steel crush washer that provides timing and secure lockup — the crush washer compresses as the birdcage is torqued, allowing the device to be timed with the closed bottom at the 6 o’clock position for proper flash suppression and dust reduction. Compatible with all AR-15 barrels chambered in 5.56 / .223 with 1/2×28 threads, including 10.5″, 14.5″, 16″, 18″, and 20″ barrels, carbine, mid-length, and rifle gas systems, and with all AR-15 upper receivers. Whether you are completing a mil-spec M4 clone build, building a budget range rifle, replacing a damaged muzzle device, or needing a placeholder muzzle device until your suppressor mount arrives, the A2 birdcage is the proven, reliable, inexpensive solution that has served on millions of M16 and M4 rifles worldwide.
The original, proven flash hider that reduces muzzle flash, reduces dust signature, and protects your muzzle crown at a throw-in price.
1. Mil-Spec 5-Slot Design with Closed Bottom for Flash Suppression and Reduced Dust Signature: Flash suppression matters for low-light shooting — muzzle flash that blinds the shooter and reveals position compromises night shooting, tactical training, and defensive use — a bare muzzle or aggressive brake produces a fireball that destroys night-adapted vision for seconds. The A2 birdcage uses five radial slots positioned on the top and sides with a solid, closed bottom — when high-pressure gases exit, the slots vent gas outward and upward in five separate, cooler jets that mix with ambient air and cool before igniting, breaking up the single large fireball into small, dim flashes that are significantly less visible to both shooter and observer. The closed bottom serves two purposes — it prevents gas from venting downward and creating a dust cloud when shooting prone, in sandy environments, or from a bench that would obscure the target and reveal position, and it provides a small amount of compensation that pushes the muzzle down slightly to counteract muzzle rise, though not as much as a dedicated brake. The A2 is not a muzzle brake — it does not significantly reduce recoil — it is a flash hider first, designed to hide flash, not to control recoil — for shooters who want recoil reduction, choose a brake or compensator, but for shooters who want reduced flash and reduced dust signature at minimal cost and weight, the A2 delivers proven performance that has been combat-tested for 40+ years on M16A2, M4, and M4A1 rifles. The birdcage profile also provides some protection against muzzle strikes that would damage the crown.
2. Mil-Spec 4140 Steel with Phosphate Finish and Included Crush Washer for Secure Installation: Muzzle devices live in extreme heat and fouling — direct exposure to 3000-degree gases and carbon buildup that erodes cheap aluminum or low-grade steel devices within a few thousand rounds. This A2 birdcage is machined from 4140 carbon steel bar stock — the same steel used for barrels — not cast or MIM — with CNC machining for a concentric bore that prevents baffle strikes and accuracy degradation, and with 1/2×28 TPI threads that are Class 2A fit for secure engagement with barrel threads without wobble. The finish is mil-spec manganese phosphate — parkerized black — that matches standard barrel phosphate finishes and provides corrosion resistance and oil retention that prevents rust, even when exposed to rain, sweat, and humidity — phosphate is more durable than painted finishes that burn off. The package includes a standard USGI-pattern steel crush washer — a single-use, compressible washer that sits between the birdcage shoulder and barrel shoulder — as the birdcage is torqued to 15-20 ft-lbs, the washer crushes and allows precise timing of the closed bottom to the 6 o’clock position — the closed bottom must face down for correct function — the crush washer provides secure lockup that prevents the device from loosening under vibration and recoil without needing Loctite or permanent installation. The crush washer also provides a small amount of spring tension that maintains torque. This is a complete, ready-to-install package — no need to source the washer separately.
3. Universal 1/2×28 Fit for All 5.56 / .223 AR-15 Barrels and Lightweight, Compact Profile: Building an AR-15 requires parts that fit without gunsmithing — muzzle devices with incorrect thread pitch or non-concentric bores cause baffle strikes, accuracy loss, and dangerous projectile deflection. This A2 birdcage is threaded 1/2×28 TPI — the universal, standard thread for AR-15 barrels chambered in 5.56 NATO / .223 Remington — fits 99% of AR-15 barrels with that thread, including 10.5″ pistol, 14.5″ M4, 16″ carbine, 18″ SPR, and 20″ rifle barrels, with carbine, mid-length, and rifle gas systems, from all manufacturers — Anderson, Aero, Ballistic Advantage, Faxon, PSA, etc. — and works with both forged and billet uppers. The A2 is lightweight at approximately 1.8 oz and compact at 1.75″ in length — adds minimal weight and length to the rifle compared to 3″ brakes that add 3+ oz and significant length — keeps the rifle handy and balanced. It is also suppressor-hostile — it does not provide suppressor mounting — but for shooters not running a suppressor, it is the most economical and lightweight option that still provides flash suppression and crown protection. Whether you need a final muzzle device for a budget build, a placeholder until your KeyMo or Plan B mount arrives, or a replacement for a damaged device, this A2 birdcage with crush washer installs in minutes with a standard armorer’s wrench and delivers mil-spec function at a price that makes it a throw-in add-on.
The AR-15 Mil-Spec A2 Birdcage W/Crush Washer 5.56 delivers mil-spec 4140 steel construction, 5-slot flash suppression with closed bottom, and included crush washer for secure timing.
Type: AR-15 Mil-Spec A2 Birdcage Flash Hider With Crush Washer – 5-Slot Birdcage with Closed Bottom – Flash Suppression and Dust Signature Reduction. Material: 4140 Carbon Steel Bar Stock – CNC Machined – Manganese Phosphate / Parkerized Black Finish – Corrosion Resistant. Caliber: 5.56 NATO / .223 Remington – .22 Caliber Bore – Optimized for .223/5.56 – Not for .30 Caliber. Thread: 1/2×28 TPI – Standard AR-15 5.56 Thread – Class 2A Fit – Concentric Bore to Prevent Baffle Strikes. Function: Breaks up the gas column into Cooler Jets to Reduce Visible Muzzle Flash – Closed Bottom Prevents Dust Kick-Up When Prone – Protects Muzzle Crown from Impact. Compatibility: All AR-15 / M4 / M16 Barrels with 1/2×28 Threads – 10.5″, 14.5″, 16″, 18″, 20″ – Carbine, Mid, Rifle Gas. Installation: Includes Steel Crush Washer – Torque 15-20 ft-lbs – Time: Closed Bottom to 6 O’Clock – Wrench Flats for Armorer’s Wrench. Weight / Length: Approx. 1.8 oz / 1.75″ Long – Lightweight, Compact.
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