5.56 x 45mm United States
Details
| Type | Blank, M200 |
|---|---|
| Projectile | [none] |
| Case | brass, 7-petal crimp, purple lacquer sealant, 1 knurled cannelure |
| Primer | percussion, flat, brass, ring crimp, red annulus |
| Headstamp | T W 7 0 |
| Notes | The purple crimp sealant was used instead of the previously-used white paint to try to prevent gas port fouling. |