.303 British, or 7.7x56mmR, is a .311 inch calibre rifle and machine gun cartridge first developed in Britain as a blackpowder round put into service in December 1888 for the Lee-Metford rifle
The rugged Forerunner 310XT is the triathlete's indispensable training tool — a GPS-enabled, swim-proof trainer that tracks bike and run data and sends it wirelessly to your computer.