 The boat-tailed bullet design of Mk 8 ammunition is not in itself a problem.However, when combined with the cordite propellant used in Mk 8 cartridges, which burns at a much higher temperature than nitrocellulose, there is increased barrel erosion.The cumulative effects of firing Mk 8 ammunition through rifles were known during the Second World War, and British riflemen were ordered to avoid using it, except in emergencies.