A muzzle loading weapon having a bullet propulsion system for the propulsion of a bullet from a bullet chamber, the chamber comprising a first portion to receive combustible powder and a second portion to receive the bullet, characterised in that a blocking element is fixedly located in operable communication with the powder receiving portion of the chamber and distal to the bullet receiving portion of the chamber, a flash hole being provided in the blocking element, a replaceable end cap being locatable over the blocking element, a primer being associated with the end cap, whereby detonation of the primer serves to ignite powder in the bullet chamber via the flash hole, thereby to cause combustion of the powder and propel a bullet from the chamber, provides greatly improved accuracy and efficiency.