sentences:  When the 6.5×68mm was introduced in 1939 it probably held the title of fastest production cartridge on the market.Nowadays there are commercial cartridges on the market which offer even higher muzzle velocities.The American .264 Winchester Magnum cartridge introduced in 1959 and the French 6.5×63mm Messner Magnum are probably the closest ballistic twins of the 6.5×68mm.