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 Model: Bushmaster XM15 E2S M4A3-Type/Colt M4 and M4A1/ArmaLite M15 A2 and A4

Nickname: M4

Caliber: .223 Remington (5.56x45mm NATO)

Operation:
Semi/Full Auto, Semi/Burst, Semi (depending on model), direct gas operated, locking bolt

Overall Length: 33"

Barrel Length: 14.5"

Weight: 5.65 lbs.

Accessories:
Colt M203 grenade launcher, Trijicon 4x ACOG scope, removable carry handle (depending on model)
As with the full-size AR15, there are many versions of the AR15 carbine, and the Trio have a lot of them.