1) The rifling grooves ran straight for the first 4 feet (1.2 m) and then spiraled with a gradually increasing twist towards the muzzle.

2) The Rate of Fire figure given above is found in references for British guns of this caliber, but "Warrior to Dreadnought:  Warship Development 1860-1905" quotes Jellicoe's 1906 figures for rates of fire for these guns in gunlayers' tests and in battle practice and notes that the latter figures corresponded well to those actually attained by the Japanese at Tsushima:

Gunlayers Test:  2 rounds per minute
Battle Practice:  1 round per minute

3) The submarine gun could only be reloaded on the surface.  The procedure was to do a submerged approach a target to within 1,200 yards (1,100 m), drive the submarine to the surface, quickly fire the gun and then dive back down.  It is apparently a myth that the gun would normally be fired with only the muzzle out of the water when attacking an enemy, as such a condition would mean that the gun was at its maximum elevation while the sighting periscope would be at a minimum height out of the water.  Such a combination would mean an extremely slight chance of hitting anything.

1) Projectile weights from ADM 186/169.  The sources below disagree as to the muzzle velocity for these guns.  I have chosen to use those values given in "Warship Volume V" by John Campbell.

2) Early ships carried 2crh shells.  4crh was carried by ships with 30 degree mountings and by the submarines.

3) The BVI mounting originally had two ready-use rounds per gun in the gunhouse, later increased to five rounds.  There were eight more rounds per gun stowed in the working chamber which could be accessed via a winch should the shell hoists suffer a breakdown.

1) The sources below disagree as to the maximum ranges and muzzle velocities of these guns.  I have chosen to use those values given in "British Naval Guns 1880-1945 No 4" by John Campbell.

2) It should be mentioned that these maximum ranges were of little use at the time these ships were built.  Fire control systems and rangefinders capable of accurately firing at ranges over 10,000 yards (9,140 m) were nonexistent.

Single Mount
   Submarines (1)

Submarine:  N/A

1) The BVI mounting was a rotating stalk design with a shell chamber below the gunhouse.  The ammunition hoist was interrupted at the shell chamber rather than continuous from the magazine to the gunhouse.  Shells were delivered horizontally to the shell chamber where a grab picked them up and delivered them to the gunhouse hoist.  From a sketch, this gunhouse hoist appears to be a three level cage with the shell on top and half charges in the lower compartments.  This mounting was also designed with safeguards against a cordite fire in the gun chamber flashing down the ammunition tube into the magazine.

2) The BVI mounting had a secondary bogie for hand-loading fitted at the rear of the gun and aligned at 1 degree elevation.

3) The BVII mounting achieved the long-sought British goal of any angle loading, a featured carried through on subsequent ships until it proved impractical on the 15"/42 (38.1 cm) Mark I twin mounts.

4) The submarine mount needed to be loaded and fired on the surface, although some trials had just the muzzle of the gun above the water.  The muzzle was fitted with an electrically-operated, water-tight tampion.  The gun mounting was free-flooding, thus allowing quick access after surfacing.

5) Commonwealth and Zealandia were altered in 1918 to allow an elevation range of -3 / +30 degrees.