Last reviewed: 2026-04-19 by Jake Terry, FFL07/SOT3, NRA-certified firearms instructor.
The Winchester M855 SS109 5.56x45mm NATO ammo is a green-tipped, steel-core penetrator round designed to NATO military specifications. Chambered in 5.56 NATO — not .223 Remington — this 62-grain full metal jacket load clocks 3060 feet per second at the muzzle and delivers 1289 foot-pounds of energy. You get 1000 rounds packed in 50 boxes of 20, brass-cased and boxer-primed for reloadability. If you run an AR-15 or similar platform chambered for 5.56, this is the NATO-spec green tip that meets the original SS109 military standard.
Performance at a Glance
Winchester loads the M855 with a steel core and a gilding metal jacket, capped by the signature green penetrator tip. The 62-grain projectile stabilizes in 1:7 and 1:9 twist barrels and provides barrier-capable performance against intermediate materials. The brass case is non-corrosive, reloadable, and sourced domestically. Winchester manufactures this ammunition in the United States to NATO specifications — meaning chamber pressure and velocity exceed commercial .223 Remington loads. Do not fire 5.56 NATO rounds in rifles marked “.223 Remington only.”
Specs at a Glance
| Spec | Value |
|---|---|
| Caliber | 5.56x45mm NATO |
| Bullet weight | 62 grains |
| Bullet type | Penetrator Full Metal Jacket |
| Muzzle velocity | 3060 fps |
| Muzzle energy | 1289 ft-lbs |
| Rounds/box | 1000 (50 boxes of 20) |
| Case | Brass |
| Primer | Boxer |
| Corrosive | No |
| Reloadable | Yes |
| Velocity rating | Supersonic |
| Intended use | Range & Target |
| Manufacturer | Winchester |
This load is optimized for semi-automatic rifles chambered in 5.56 NATO with 16-inch to 20-inch barrels. The steel core offers improved performance against light barriers compared to standard 55-grain M193 ball, though it remains a range and target round rather than a dedicated barrier-defeating penetrator. M855 green tip 5.56×45 ammo is widely available, affordable in bulk, and accepted at most outdoor ranges. Verify your range’s steel-core policy before ordering.
Who It’s For
Shooters running carbine drills, defensive rifle courses, or high-volume plinking sessions where barrier capability matters more than soft-target expansion. This is not a hunting or personal-defense load — the full metal jacket will not expand on impact. It is a training and marksmanship round that mirrors military ball ammunition. If you reload, the boxer-primed brass cases offer reuse value. If you shoot a .223 Remington bolt-action or AR marked “.223 only,” do not use this ammunition — the NATO chamber pressure will exceed SAAMI .223 specs.
Safe Handling & Compliance
Federal law requires purchasers to be at least 18 years old for rifle and shotgun ammunition, and at least 21 for handgun ammunition. Ammunition cannot be shipped to certain states, counties, and cities — review our ammunition shipping restrictions before ordering. Store ammunition in a cool, dry location away from heat sources and out of reach of unauthorized users.
- Observe the four rules of firearms safety: treat every firearm as if it is loaded, never point at anything you do not intend to shoot, keep your finger off the trigger until ready to fire, and be certain of your target and what lies beyond it. Learn more in our firearms safety guide.
- Verify that your firearm is chambered for 5.56 NATO before firing this ammunition. Do not use in rifles marked “.223 Remington” or bolt-action sporting rifles unless the manufacturer explicitly approves NATO-spec loads.
- This product contains lead, a chemical known to the State of California to cause cancer and reproductive harm. Use adequate ventilation when shooting indoors and wash hands after handling ammunition. See California Proposition 65 for more information.
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