 The muzzle booster increased the recoil force transmitted to the barrel by directing some of the escaping gas into pushing the barrel back rather than letting it all expand outwards at the muzzle, in essence acting as an auxiliary gas-operating system, with the barrel acting the role of the operating rod.This increased the initial velocity of the barrel and bolt, providing more energy for the operation of the mechanism.A Vickers-type booster (the "typical" muzzle booster type) consists of two parts; the first is a flared "cup" on the muzzle of the barrel and the second is a perforated tube around the end of the muzzle, attached to the main body of the weapon, and with an end closed except for a small hole for the bullet to pass through.