The ammunition to be used was the 105 mm Fd Mk 2 ammunition used in the L13 ordnance of the gun equipment 105 mm L109 (better known as the "Abbot self-propelled gun"). This ammunition uses electrical instead of percussion primers and is an entirely different design from the US M1 type ammunition as used in the L5 pack howitzer. The two types are not interchangeable. An early requirement was for the new weapon to use 105mm Fd Mk 1 ammunition, which uses the M1 shell, in training. However, in 1968, this was changed to allow a different version of the weapon, which subsequently became the L119, to fire US 1935 pattern (i.e. M1) ammunition.