1) The firing mechanism was electric or percussion with vent sealed tubes and the guns could not be fired unless the breech was fully seated.

2) The guns were designed for either a right or left hand breech, but the barrels were interchangeable.

3) Caesar, Illustrious and the Canopus class had the improved BIII mounting (see below) which included two hydraulic rams for loading and other improvements.  Vengence added an improved chain rammer designed by Vickers which allowed any angle loading.

1) The sources below disagree as to the projectile weights, propellant types, propellant weights and muzzle velocities.  This may be due to the rapid transition from black powder to cordite in the late 1800s and the attendant experimentation with differing mixtures.  I have chosen to use those figures given in "The Big Gun" for AP rounds and those in "Big Gun Monitors" for HE rounds.

2) HE 4crh and HE 8crh projectiles were issued only to monitors.  The original AP 2crh was solid shot.

Monitors:  -0 / +30 degrees

For other classes and for Caesar and Illustrious
   13.5 degrees
   Any angle of train

Vengeance
   Any angle of elevation or train

1) These mountings were designed by Elswick and had thickly armored gunhouses, a significant improvement over the open barbettes of the previous Royal Sovereign class.  The mountings were of progressively better design, each one being used on a few ships until an improved version was available which in turn would be superseded by a newer version.  The BII was pear shaped while the BIII and later mountings were circular.  The latter meant that these ships could now be loaded at any angle of train.  This mounting also instituted a shell room below the gunhouse.  These were the first British ships that had a break in the ammunition supply, which gave them an increased safety factor.  Ammunition hoists were two stage, the first running from the magazines and shell rooms to the shell room with the second stage up to the gunhouse.

2) The BII was the first British mounting where the training mass was balanced about the center of rotation and the elevating mass was balanced about the trunnions, thus allowing for hand-training of the mounts as well as lighter training engines.  The guns were also well-balanced, even with the guns in the run out position, allowing for lighter elevating gear and hand-powered backup.  These mountings were hydraulically powered.

3) One source says the revolving weight was 264 tons (268 mt), which probably includes ammunition.

4) The mountings for the monitors were reworked to allow +30 elevations in order to achieve the longer ranges needed for shore bombardments.  This higher elevation increased the recoil and run-out forces, requiring higher hydraulic pressures to be maintained.  This led to frequent breakdowns, as the leather gaskets and brazed pipe joints could not handle the increased loads.  Commented Rear Admiral Reginald Bacon, commander of the Dover Patrol, "Every day some pipe burst or some portion of the turret mountings gave out.  The cause of these troubles was a simple one; these ships had turrets taken from old battleships of the [Majestic class].  Taken straight from these ships and mounted in the monitors, the copper pressure pipes, having become crystalline with age, did not stand the re-erection.  New stresses during the fresh coupling up were set up and breakdowns occurred."

5) Although normal loading of the Majestic class was at 0 degrees train, there was stowage for 16 ready-use rounds inside each gun shield.  This allowed the guns to remain on target rather than returning to 0 degrees train for reloading between shots.  When these mountings were reused on the monitors, the external rammer was removed which allowed an increase in stowage to 20 ready rounds.  However, when these were used up, the mounting did have to return to 0 degrees train in order to replenish the ready-use ammunition.

6) Vengeance was equipped with a new Vickers chain rammer that permitted loading at any angle of elevation.