5.56 x 45mm United States
Details
| Type | Dummy |
|---|---|
| Projectile | FMJ, GM, 1 knurled crimping cannelure |
| Case | brass, taper crimp, black stained |
| Primer | percussion, flat, brass, ring crimp |
| Headstamp | R A 6 4 |
| Notes | Primer is pierced. This may be for a civilian contract. |