The Winchester USA 5.56x45mm NATO M855 62-grain Green Tip Full Metal Jacket (FMJ) Brass 20-round box is a full-power, military-specification centerfire rifle cartridge engineered specifically for AR-15 platforms, 5.56 NATO-chambered carbines, duty-replicate training, and high-volume tactical training. A primary friction point when running reduced-pressure commercial .223 Remington loads in hard-use 5.56 NATO platforms is sluggish bolt velocity, inconsistent gas port impulse, and potential short-stroking during rapid-fire strings. Winchester resolves these cycling limitations by loading this M855 ammunition to true 5.56 NATO pressure standards, delivering robust bolt carrier velocity, positive ejection, and reliable function across direct impingement and piston-driven gas systems.
The primary technical advantage centers on the standardized M855 projectile architecture. Featuring an iconic green-painted tip, the 62-grain Full Metal Jacket bullet houses a hardened steel penetrator seated ahead of a rear lead core, wrapped in a precision copper jacket. This dual-core layout shifts the projectile's mass distribution forward to enhance gyroscopic flight stability when fired through 1:7 or 1:8 twist-rate barrels. Combined with a 0.304 G1 ballistic coefficient, the bullet resists crosswind deflection, maintains velocity downrange, and delivers predictable external ballistic trajectories.
Launching its 62-grain steel-penetrator projectile at a factory-rated 3,060 FPS muzzle velocity, this Winchester USA loading delivers flat shooting performance and hard-hitting downrange kinetic energy. Assembled using heavy-duty mil-spec brass cases (produced at Lake City facilities), clean-burning propellants, and non-corrosive Boxer primers with sealed primer pockets, the cartridge ensures thermal stability and smooth extraction under high-volume firing conditions. It is an essential choice for tactical rifle training, carbine courses, defensive preparation, and range drills that require true M855 ballistics.
Key Benefits
- Mil-Spec 5.56 NATO Pressures: Full-power loading guarantees reliable gas system cycling, positive extraction, and zero short-stroking in AR-15 platforms.
- M855 Steel Penetrator Bullet: Dual-core design with hardened steel tip improves flight stability and barrier momentum retention.
- Lake City Brass Construction: Mil-spec virgin brass casings feature sealed primers for long shelf life and high reloadability.
- 3,060 FPS Muzzle Velocity: Delivers flat supersonic trajectories, predictable wind drift, and tight group stability in 1:7 and 1:8 twist barrels.
Technical Specification
- Ballistics: 5.56x45mm NATO | 3,060 FPS Muzzle Velocity | 0.304 G1 Ballistic Coefficient
- Projectile: 62 Grain | Full Metal Jacket (FMJ) | M855 Green Tip | Steel Penetrator Core | Lead Base | Copper Jacket
- Case/Primer: Precision Mil-Spec Virgin Brass Case | Clean-Burning Powder | Non-Corrosive Boxer Primed | Sealed Pocket
- Logistics: 20 Rounds Per Box | Winchester USA Series
- Dimensions: Standard 5.56x45mm NATO Geometry | AR-15 & 5.56 NATO Rifle Compatible | SKU: USA855K
- Application: High-Volume Target Practice, Tactical Training, Carbine Courses, Duty Replication, and Range Drills
- Standards: Mil-Spec Compliant | SAAMI/NATO Compliant | Winchester Quality Control Benchmarks
If you're running a 5.56 NATO platform and need consistent pressure, reliable cycling, and repeatable trajectory for training or drills, this load meets those requirements without deviation. Get proven mil-spec performance backed by controlled production standards—available now from SMKW, a trusted source for dependable ammunition.
