The L42A1 is a Sniper Rifle featured only in Breakthrough, the 2nd expansion of Allied Assault. It is usable by John Baker in the campaign and by the British faction in Multiplayer.
The rifle is capable to kill enemies with a single torso shot, but the ammo can be scarce and it's recoil is higher than unscoped version. The L42A1 appears in the multiplayer as the default sniper rifle for the British forces.
The L42A1 is the single best sniper rifles in the game. It outclasses the Springfield and Kar98k for its doubled magazine capacity at 10 rounds, and the use of a detachable magazine. At the same time, it maintains the recoil level of a bolt-action sniper rifle, which is markedly lower than that of a semi-automatic sniper rifle like G43 and SVT40.
Behind the Scenes
The L42A1 is based on the No.4 Enfield. It was the British Army's standard sniper rifle from 1970s until 1990s when it was replaced by the L96 sniper rifle. Hence, its appearance in a WW2-themed title is anachronistic. It is possible that the developers, like many others, were misleaded by the designation and believed the model was introduced in year 1942. The historically correct counterpart would be Lee Enfield No.4 Mk 1 T, the scoped version of the Lee Enfield No.4 Mk 1 Rifle.