5.56 x 45mm United States
Details
| Type | Blank, M200E1 |
|---|---|
| Projectile | [none] |
| Case | aluminum, greenish yellow anodized and teflon coated |
| Primer | percussion, flat, brass, ring crimp, red annulus |
| Headstamp | F A 7 4 |
| Notes | This is a primed but otherwise unfinished M200E1 extended-neck blank case. |