 Firstly it allows for a smaller turret volume, as no internal space is needed for the vertical movement of the gun breech.Secondly, it allows the use of a relatively simple semi-automatic auto-loader fed by multiround magazines, achieving a very high rate of fire for as long as the magazines were loaded, as the gun is also fixed with respect to the auto-loader located in the back of the upper turret, i.c.a protruding bustle.