- "Simmmonns...I-I can'tt ffeeel my handdds."
- "Maybe you should lay off the trigger, you dumbass."
- —Simmons in Motion to Adjourn
The Assault Rifle is a firearm that many characters in the series have used. Caboose has wielded it as his primary and signature weapon since Reconstruction and has also been seen using it to fight the eternally spawning Grunts at Battle Creek. Tex used one from Season 1 to Season 3 until she began to use the Battle Rifle. It was also used by Lopez during Season 1. Simmons and Grif both carried one in Season 1 and Season 2, (such as in the attack on Blue Base at the start of Season 2).
Although the Battle Rifle has replaced most Assault Rifles, the Assault Rifle is still used, as all the Blues at Rat's Nest were seen carrying them in Reconstruction. Washington used one as well when he was attacked by a Hornet in Reconstruction. In Season 9, it is used by the Insurrectionists frequently. South Dakota also commonly used an Assault Rifle in Season 10. In the episode C.T., Florida uses an Assault Rifle loaded with explosive ammunition to eliminate Chain Guy and Chain Girl during the battle at the Longshore Shipyards. The Federal Army of Chorus also primarily use the assault rifle. In addition, Freckles is moved into Caboose's assault rifle during Fed vs. New.
- Caboose is the only Blood Gulch team member primarily armed with an Assault Rifle as opposed to a Battle Rifle. This is seemingly to compliment the fact Caboose is the only character still wearing the older Mark V armor from the original Halo: Combat Evolved title. In season 11's beginning episodes, Caboose had received new armor (the Mark V armor was not available to players or Rooster Teeth at the time), but still carried an Assault Rifle.