With the introduction of the 55 Boys, it also became necessary to consider the development of suitable training ammunition. There were fears that firing the Boys on normal ranges exceeded safety standards and could penetrate the backstops and increase the danger area behind it as many ranges were not designed to fire such powerful rounds as the Boys. The army therefore had two choices in developing practice ammunition that was less likely to cause damage to the ranges while still being able to train with the Boys rifle. The first option was a reduced calibre cartridge fired from a modified Boys rifle and the second option was specially designed ammunition that was still fired from a standard rifle. In 1937 a reduced calibre rifle was developed with a .303-inch bullet. Trial reports in 1938 however stated that the recoil was too light, while the goal of the exercise was to accustom troops to the recoil of the Boys, which was considerable. There was a joke among the troops that it took three men to fire a Boys rifle, one to pull the trigger and two to make him do it again. The 55/303 was therefore rejected and instead a full-size Boys practice round was introduced with a reduced load that was designated the P Mark 1 and was identified by a blue band just above the belt. There is a very good discussion on the 55/303 Modified Boys Rifle HERE.