Abstract : In this paper we present a novel Fiber Bragg Orating based system to provide real time monitoring of Round Exit Velocity (REV). REV can be used for automatic fuse setting in air burst munitions and as an indication of gun system performance. The REV data provided by this system can also be used to improve aiming accuracy, and to monitor barrel wear and corrosion. In this research, a prototype REV measurement system was designed, fabricated and tested on the 25 mm M242 Bushmaster cannon. Live fire tests were conducted in single shot and burst modes with various service rounds. The results of these test showed that measured REV was accurate to within 2-3% of a reference muzzle velocity radar reference system. The results also showed that REV could be accurately measured for each round in a burst at the standard M242 burst firing rates of 100 and 200 rounds per minute. The sensor system adds negligible mass to the weapon system and it is rugged and reliable.