Last reviewed: 2026-04-18 by Jake Terry, FFL07/SOT3, NRA-certified firearms instructor.
The Winchester M193 5.56x45mm NATO load is a 55-grain full metal jacket cartridge built for training, competition, and high-round-count range sessions. Winchester’s M193 designation mirrors the U.S. military’s original 55-grain ball specification — a standard that’s defined 5.56 NATO performance since the 1960s. The full metal jacket projectile does not expand on impact, making it ideal for paper, steel, and formal target work where over-penetration is managed by backstop design. Each round is assembled in Winchester facilities using new brass cases, non-corrosive boxer primers, and propellant metered to deliver 3180 feet per second from a 20-inch test barrel.
Load Profile
The 55-grain bullet sits at the lighter end of the 5.56 spectrum, trading sectional density for flat trajectory and mild recoil. At 3180 fps, muzzle energy registers 1235 foot-pounds — enough to cycle gas-impingement and piston ARs reliably across a wide range of barrel lengths and gas-system configurations. The FMJ’s copper-washed gilding metal jacket over a lead core ensures consistent feeding from STANAG magazines and predictable ballistics downrange. Brass cases headstamp with Winchester’s commercial markings and reload cleanly once fired; boxer primers punch out without hassle.
Specs at a Glance
| Spec | Value |
|---|---|
| Caliber | 5.56x45mm NATO |
| Bullet weight | 55 grains |
| Bullet type | Full Metal Jacket |
| Muzzle velocity | 3180 fps |
| Muzzle energy | 1235 ft-lbs |
| Rounds/box | 300 (ammo can) |
| Case | Brass |
| Primer | Boxer |
| Corrosive | No |
| Reloadable | Yes |
| Velocity rating | Supersonic |
| Lead free | No |
| Intended use | Range & Target |
| Country of origin | United States |
| Manufacturer | Winchester |
This load ships in a military-style ammo can holding 300 rounds — ten 30-round magazine loads with no loose rounds. The can’s metal construction and rubber gasket keep moisture out during transport and storage. For more Winchester 5.56×45 Ammo options, review our full catalog.
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 universal rules of firearm safety at all times — treat every firearm as loaded, keep your finger off the trigger until ready to fire, never point the muzzle at anything you’re not willing to destroy, and know your target and what lies beyond it.
- Verify current state and local laws regarding ammunition purchase, possession, and use in your jurisdiction.
- This ammunition contains lead. Wash hands thoroughly after handling. Pregnant women and children should avoid exposure. Shoot in well-ventilated areas and follow range environmental protocols.
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