The gun and carriage were said to be mounted en barbette, that is to say on a sloping iron platform behind a parapet over which the muzzle protruded in the firing position. While the centre of the platform was secured to a pivot set in the concrete gun floor, each end of it stood on a pair of 'trucks', or small flanged wheels, which ran on a circular rail set in the floor. Thus the complete equipment could be traversed through any angle up to 360° according to the sector the gun was expected to cover.

On firing both gun and carriage recoiled up the sloping platform, being held there while the gun was reloaded. Loading completed, gun and carriage were released to run out down the platform to the firing position once again.