5.56 x 45mm United States
Details
| Type | Ball, XM777 |
|---|---|
| Projectile | FMJ, GM, steel core, black tip, 1 knurled crimping cannelure |
| Case | brass, taper crimp |
| Primer | percussion (fired), flat, brass, ring crimp |
| Headstamp | L C 7 8 |
| Notes | This appears to be an inert loading rather than a misfire, since identical rounds with a deep primer dent exist in other collections. |