Chief EG-X
From Halopedia, the Halo wiki
File:L 46490758bebe86a15a660ab90633e3dc.jpg
Pic of the Bullet Casing
In Halo 3, if you play a multiplayer match, and then fire a bullet and pause the video afterwards, fly over to the casing, and look at the back of it. It says Chief EG-X. Sometimes small patterns can be seen. This is on the Battle Rifle, Assault Rifle, Pistol, Sniper Rifle, and Machine Gun Turret.
you can also look at the smoke of the rocket and see that it spells 117
