What caliber bullet does the AR-15 fire and how many rounds per minute can it fire fully automatic?

The AR15 has a rate of fire of 650-750 rounds/min (M16A1) or 700-950 (M16A2/M16A4). Calibers: .17 Remington, .17-223, .17 HMR, .17 HM2, .204 Ruger, .20.MORE?
Answered by kgb agent Romuel C on Sunday, June 24 2012 at 05:57PM EDT