The British 16" Mark I Gun and Mounting

By Terry Duncan
Updated 01 January 2004

Summary

This is a description of the path a shell took from the magazine to the gun and details of the crew duties in these controversial weapons.  Also included are details of some of the major differences between these mountings and the type originally intended for the G3 Class ships from which they were derived, and of the corrective measures taken, or under review by 1938.

Loading Arrangements

The projectiles were stored horizontally in bins set around the shell rooms, which were themselves set around the shell handling room.  They were lifted from their stowage by powerful grabs and carried on overhead conveyors to a power-operated traversing tray and a hydraulic rammer.  When operated, the rammer thrust the projectile through an aperture in the shell room bulkhead, onto a pivoted tray in the adjacent shell handling room.  A watertight door opened to allow the projectile to pass and closed as soon as the shell room rammer had withdrawn.  By having a traversing tray, it was possible to load one of its two troughs while the other was in the ramming position.

The shell handling room surrounded the revolving turret trunk, to which a pair of contra-rotating, power-driven, geared rings were attached.  These could be clutched to drive four shell bogies, set 90 degrees apart.  When three projectiles, from three separate shell rooms had arrived on the pivoting trays, the bogies were traversed around the trunk to a lined-up position, and then locked "to ship."  Each pivoting tray was then revolved until it lined up with a shell bogie and an integral tray rammer transferred the shell.  The rotating power-driven gear-rings were next connected to the bogie bodies through a complex arrangement of power drives and clutches.  The bogie, now connected to the rotating rings, was of cradle style with a geared quadrant and, in being turned through 90 degrees , it caused the shell to take up an upright attitude.  When the three bogies had thus tipped, they were "unlocked from the ship", reclutched to "traverse" and driven around the trunk until each was in line with a shell hoist.  The three shell hoists - one for each gun - were themselves displaced 90 degrees apart, so that one of the four bogies was unused.  This, referred to as the master bogie, was normally kept upright and was used solely as a position from which all four bogies were traversed.  It was, of course, used as a spare when one of the others became defective as the bogie traverse could be controlled from any of the four positions, their operating levers being mechanically linked together.

Having located the bogies opposite the shell hoists, the complete bogie ring was locked to the trunking and would then revolve with it should the turret train.  Each shell, now resting on its base, was next moved towards the hoist by the bogie rammer (again powered by the common power drive), all bogie movements being mechanically interlocked to prevent accidental malfunction.  For example, it was impossible to unlock "from ship" until all three working bogies had been tilted upright, nor would the bogie rammer function until the bogie had been locked to the trunk.

Between the shell bogie and the hoist base there was a cylindrical drum, called a scuttle which accepted the shell when it was rammed inwards.  The scuttle was rather like an enormous pistol cylinder, with two shell positions diametrically opposite each other, and it too, had to be locked before the bogie rammer could operate.  Once the shell had been transferred and the scuttle unlocked, the latter was engaged with the shell hoist mechanism.  Its down-stroke operation spun the scuttle around half a turn, placing the shell at the bottom of the hoist tube, and at the same time exposing the empty shell position.  These automatic scuttle drives gave persistent trouble and were prone to shear completely.  In 1936 the automatic feature was removed, the scuttles being modified for hand rotation, and an extra rating was added for each gun.

The shell was moved upwards towards the gunhouse by a pusher hoist that worked on the ratchet principle.  As soon as all shells had been transferred to their respective hoists, the bogies were unlocked and traversed back to the nearest convenient pivoting tray; and so the process went on until the three hoists were full.  By this time, they held a vertical column of four shells each (the highest shells having reached the gunhouse) and there were thus twelve tons of shell in the hoist trunks.

In the cordite handling room the six cordite charges were laid in trios into the hopper trays, swung into the hopper trunking and then power rammed horizontally into a double-cylinder canister.  A wire rope skip tipped it vertically upwards and hauled it to the gunhouse in one movement, where it appeared alongside the waiting shell, ready for loading.

The Gunhouse Loading Arrangements

Remembering that there were three guns in each mounting, we need only consider the loading process for one gun.  However, it is worth mentioning that the left gun breech hinged open on the left-hand side, whereas the right and centre guns had right sided breeches.  This was not particularly significant since, clearly the centre gun had to be "handed" on one side or the other, but it did, of course make the layout of the hoists in the turret asymmetrical.  British interrupted screw breech mechanisms opened, door-wise, either to the right or left, but the U.S.  favoured a mechanism hinged at six o’clock, so that, even in a multi-gun turret, the breeches were identical, gun to gun.

A gun's crew consisted of three men.  The Captain of the Gun (CoG) operated the loading control levers and the chamber wash out squirt; No2 looked after the electric firing circuits and the air-blast gear (to discharge the cordite fumes from the chamber when the breech was re-opened); and No3 worked the shell and cordite hoists by operating two levers.  He could see immediately when a shell was available by its presence at the top of the shell hoist, but had to wait until a mechanical telegraph plate moved to reveal "Cage Loaded" before raising the cordite.

The CoG now took over, operating his two hand-levers.  These were known as "churn levers" by the crews due to their motion around three sides of a square box.  Complex mechanical interlocking rods (similar to the type found beneath a railway signal box of the period) were fitted to prevent malfunction.  The first movement was towards "Lock Slide", whereupon the gun was divorced from the layers control and automatically moved, as required, in either elevation or depression, until it reached the fixed angle of 3 degrees.  There, heavy pawls engaged it, holding it rigidly.  Shifting the same lever sideways aligned it with the "Tilt Tray" tipped the tray downwards to the 3 degree loading angle.  The cordite canister, linked to the tilting gear, tipped automatically to the same angle so that both shell and cordite were now aligned alongside each other.  At this stage, however, they were to one side of the breech, clear of the guns recoil, so, as soon as the tipping motion of the shell tray was complete, it tripped a traverse gear which carried it sideways on a carriage, pulling the cordite canister after it.  At this point, the situation was;

1. Gun locked at loading angle

2. Breech open

3. Shell tray tilted and traversed to position in line with chamber

The CoG now operated his second lever towards "Ram Shell", whereupon a seven-section telescopic rammer extended from a rammer casing anchored to the turret deck plate, and thrust the shell through the chamber until its copper driving band bit into the commencement of the rifling.  When he returned it to the "Withdraw" position, it became aligned with the lateral "Traverse" slot.  Moving it in this new direction caused the whole assembly to traverse a step inwards, so bringing the first three charges into line between the rammer and the chamber.  The same lever, pulled backwards into the "Ram Cordite" slot, again extended the rammer, but its stroke was automatically reduced as the cordite did not have so far to travel as the shell.  The rammer was withdrawn by returning the lever to the "Withdraw" position again, the assembly traversing another step inwards automatically, to bring the second trio of charges into the ramming position.  The rammer was then extended for the third time, pushing the second three charges into the chamber and shunting the first three before them.

The first movement of the reverse sequence traversed the shell tray and cordite canister back towards their hoists, where the empty cordite container re-entered the hoist skip-cage and the shell tray reconnected with the hoist tilt gear.  Thereafter, the shell tray was tilted upright, the breech closed, a firing tube inserted into the lock, the slide unlocked, and the layer resumed elevation control of the gun (the gun-drill order "Free the slide" was adopted in the messes as a request to "pass the butter" and is still sometimes used today, although its significance is seldom appreciated by those using it.  So in a small way these guns are still remembered!).

Once the cordite canister had returned to the top of its hoist trunk, and the tray had been tilted upright by the CoG, No3 sent the cordite cage back down to the lower quarters for reloading and brought another shell up into the shell tray by operating his "Raise Cordite" and "Raise Shell" control levers.  The three drill positions were;

1. Gun Loaded.  Guns on pawls and loaded, no tube in vent; firing circuit interceptor open; shell tilting tray loaded; shell hoist full; cordite cage up, and full.>

2. Half-cock.  Gun loaded; tube in vent; interceptor open; gun free from pawls.

3. Gun Ready.  Gun loaded; tube in vent; gun layer "on", by matching receiver pointers; interceptor closed.

In the rear corners of the gunhouse there were two auxiliary stowage positions for shells, each with an associate radial crane capable of plumbing a striking-down hatch, through which shells could be returned directly to the shell room.  The normal shell supply arrangements, described above, were not reversible and there had to be a means of emptying the hoist and stowing the shells there from, should the type of projectile be changed during an action.  The hydraulic radial cranes could plumb the adjacent outer hoist, the shell bin and the striking-down hatch, making the process for the outer guns fairly straightforward, but the centre shell hoist was beyond the span of either crane and special slinging arrangements had to be arranged to unload it!

The 16" Gun Mounting Crew

 The full turret crew were as follows;

Gunhouse, "silent cabinet" and training engine space.

 1 captain of turret (quarters rating, 1st class).
 3 gun's crews of 3 men each.
 1 rangetaker, plus one, for rangefinder.
 1 LDS layer.
 1 LDS trainer.
 1 sight-setter.
 1 OOQ.
 1 telephone operator.

Plus for quarters firing:

 1 range officer.
 1 rate officer.
 1 Dumaresq calculator operator.
 3 Gunlayers (quarters ratings, 3rd class), senior gunlayer in charge.
 1 turret trainer.

 Shell handling room.

 1 second captain of turret (QR1).
 4 shell bogie operators.
 4 pivot tray operators.
 3 shell scuttle operators (after modifications).

 Shell room.

 1 petty officer in charge of 24 men ("B turret only - 6 men per loading tray; "A" and "X", with only three trays, had 18 men).

 Cordite handling room.

 1 petty officer plus 15 men (5 per gun).

 Magazine.

 1 petty officer, plus 24 men ("B"), or 18 ("A" and "X") - 6 men per supply scuttle manned).

  Guncrew Duties.

 1.  Gunhouses etc (see earlier descriptions).

 2.  Shell Handling Room:
   (i) Pivot tray number - loads shell bogie and operates serving port.
  (ii) Shell bogie number - controls the bogie and loads the revolving scuttle at the hoist.
 (iii) Shell scuttle number - revolves scuttle by manual operation.

Loading Procedure

 (i) opens serving port.
 (i) of shell room, advances shell room rammer; withdraws rammer, trains pivot tray into line with shell bogies.
 (ii) puts bogie tilt lever to "Tilt Lift"; when bucket is horizontal, replaces tilt lever to "Locked to ship".
 (i) advances pivot tray rammer; withdraws pivot tray rammer.
 (ii) puts bogie tilt lever to "Tilt Right"; when bucket is vertical, replaces tilt lever to "Locked to ship".
 (i) trains pivot tray back to serving port.
 (ii) of master bogie, puts churn lever to "Train Right" or "Train Left".
(ii) of other bogies, put their churn levers to "Locked to Trunk" (Note:  All bogies lock to trunk automatically when in line with hoist).  In the case of "B" only, its fourth tray was initially loaded but then remained in line with its serving port.
(ii) of loaded bogies, ram projectiles into scuttles, withdraw rammers and clutch scuttle "To Hoist" as soon as rammers have withdrawn (Note:  Drill changed when scuttles were modified).
 (ii) of master bogie, trains back to pivot trays.
(ii) of working bogies, lock bogies "To Ship" and tilt buckets to horizontal (Note:  The master bogie is kept free with bucket vertical).
 The cycle was repeated until the shell hoists were full and the tilting trays in the gunhouses were loaded.

State on completion of "Load Hoists"

 1.  Shell hoists full.
 2.  Shell scuttle loaded and clutched "To Hoist".
 3.  Shell bogies loaded and "Locked to Ship".
 4.  Pivot trays loaded and in line with serving ports.
 5.  Serving ports closed.

At the order "Load"

 When scuttle has rotated, (ii) of working bogies "Lock to Trunk", reload scuttles, clutch scuttles "To Hoist" and free bogies from trunk.

Duties of shell room crew

 PO takes general charge in the main shell room.
 No1 (in charge of the crew) works rammer of traversing tray.
 No2 traverses tray.
 No3 removes grab at traversing tray.
 No4 works lifting and traversing levers of the overhead shell gantry.
 No’s 5 & 6 work in shell bins, placing grabs.

Duties of cordite handling room crew

 PO takes general charge of all cordite supply.
 No1 operates cordite rammer and is in charge of hoppers.
 o2, 3, & 4 - cartridge supply numbers.
 No5 operates flashtight scuttle between handling room and magazines.

Loaded State

 1.  Cordite cage up and loaded.
 2.  Cage telegraph showing "Cage Not Down".
 3.  Both hoppers loaded and closed.
 4.  Flashtight scuttle open to cordite handling room, closed to magazine, and empty.
 5.  No other cordite in handling room.

 Procedure to test cordite loading gear.

 1.  "Open right hopper" No3 opens right hopper.
 2.  "Advance rammers" - should not be possible.
 3.  "Close right hopper, open left hopper" - No3 closes right hopper, No2  opens left hopper.
 4.  "Advance rammers" - should not be possible.
 5.  "Close all hoppers" - No2 closes left hopper.
 6.  "Out cordite rammers" - No1 advances rammers.
 7.  "All cordite rammers out" - report passed to captain of turret.
 8.  "Open both hoppers" - should not be possible.
 9.  "Withdraw rammers" - No1 withdraws rammers.
10.  Cordite cages can now be raised.

Safety Interlocking Gear

The following list of the interlocks is taken from the operating instructions, and is to say the least, a little daunting!

Gunhouse Controls

  1.  Cannot put lever to "Open Breech" until slide locking pawls are out.
  2.  Cannot put lever to "Close Breech" until shell tray is tilted up.
  3.  Cannot put lever to "Tilt Down" while the hoist is on up stroke.
  4.  Cannot put lever to "Tilt Down" until breech is open.
  5.  Cannot put lever to "Tilt Up" while ramming or traversing.
  6.  Cannot put lever to "Ram" until shell tray is tilted down, or while trays are traversing.
  6A.  Cannot put lever to "Ram Shell" after trays have traversed to cordite loading position.
  7.  Cannot put lever to "Traverse" with trays tilted up.
  8.  Cannot put lever to "Traverse" unless rammer is right back.
  9.  Cannot put cordite hoist lever to "Lower" unless cordite tray is tilted up.
  9A.  Cordite tray cannot be tilted up unless cordite tray is at top of hoist to receive canister.
 10.  Cannot put cordite hoist lever to "Raise" when bottom flash door is open, or until it has been opened and closed since the hoist was last lowered.
 11.  Cannot put shell hoist lever to "Lower" until hoist has completed an upstroke.
 12.  Cannot put shell hoist to "Raise" until shell hoist has completed a down-stroke.
 13.  Cannot put shell hoist to "Raise" unless shell tray is tilted up and empty.
 13A.  Cannot put lever to "Tilt Down" while shell hoist lever is being put to "Raise", and vise versa.
  A.  Cannot put ramming lever to "Withdraw" until shell ramming stroke is complete.
  B.  Cannot put ramming lever to "Withdraw" until cordite ramming stroke is complete.

Additional notes on gunhouse controls

  1.  Slide could also be locked by a hand operated bolt.
  2.  No 1A interlock (slide cannot be unlocked unless breech is closed) removed during development; replaced by No1 (later reinstituted - see modifications).
  3.  The cordite cage could not be raised unless the cordite room rammers had been withdrawn.

Shell Handling Room

 15.  Cannot put pivot tray levers to "Slew" or "Ram" unless shell room rammer head is back.
 20.  Rammer lever on pivot tray is locked until shell bucket is horizontal.
 21.  Bogie is "Locked to Ship" until telescopic portion of pivot tray is home.
 21A.  Shell bogies cannot be "Unlocked from Ship" unless pivot tray is trained to a serving port.
 22.  Shell bucket of bogie cannot be tilted to vertical until pivot tray is clear.
 23.  Bogie cannot be "Unlocked from Ship" unless shell bucket is vertical.
 24.  Cannot put pivot tray lever to "Slew" unless bogie is "Locked to Ship"
 28.  Cannot put bogie lever to "Ram" unless bogie is "Locked to Trunk" and shell scuttle is locked in the receiving position.
 29.  Cannot "Unlock bogie from Trunk" unless bogie rammer is right back.
 31.  Cannot "Unlock bogie from Trunk" until shell scuttle has been clutched "To Hoist".
 38.  Cannot put pivot tray lever to "Slew" unless rammer lever is to "Withdraw".
 39.  Cannot put lever to "Slew" while pivot tray lever is out.
 40.  Cannot put lever to "Ram" unless slewing lever is hard over to "Train Bogie".
 41.  Cannot put lever to "Ram" unless pivot tray is in line with serving port.

Shell Room

 14.  Cannot put rammer lever to "Ram" until watertight door is open.
 14A.  Cannot put rammer lever to "Ram" until pivot tray is in line with serving port.
 16.  Cannot put watertight door operating lever to "Close" until shell room rammer is fully retracted.

 Cordite Handling Room.
 33.  Cannot move loading lever to "open Bottom Flash Door" unless both hopper doors are closed.
 34.  Cannot put loading lever to "Ram" until bottom flash door is fully open.
 35.  Cannot put loading lever to "Withdraw" until rammer has completed its stroke.
 36.  Cannot put loading lever to "Close Flash Door" until rammer is right back.
 37.  Cannot open hopper doors until bottom flash door is closed.

Early Problems

The mountings were installed during 1926-27 and the gear gave trouble almost immediately.  In July 1927 Rodney's (and Nelson's too, upon inspection) roller paths showed that the inner edge of the lower roller paths were cutting into the flanges of the turret rollers.  Initially, training speeds were reduced while a set of vertical rollers were made to take the side thrust of the rotating mass.  Upon the fitting of these, the training speed restriction was lifted, and the no further excessive wear took place.

1932:  The shell handling room pivoting tray rammers in Nelson's "B" turret were changed from wire operation to hydraulic ram, and "signal box" interlocks were introduced for all pivoting tray operations.

1931-32:  Arrangements for leading electric power on to the rotating structure were changed from cable winding gear to cable platform gear.

1933-34:  All turrets in both ships were modified as above.

1933-34:  The original automatic tray traverse mechanism in the gunhouse was changed as an outcome of a modification suggested by Chief Ordnance Artificer (COA) Waterson (thereafter known as "Waterson's Mod".

May 1934:  For the first time, Nelson's mountings were subjected to a test of prolonged firing of 16 rounds per gun.

Dec 1934:  A conference, attended by representatives of the Home Fleet, Admiralty, and gunnery experts from HMS Excellent, was held in Nelson to discuss material breakdowns.

July 1935:  The gunslide on the right of "A" mounting in Nelson was found to be cracked, and similar cracks were found in the centre gun slide of "B" in Rodney.

May-June 1936:  Persistent shearing of the drives from the shell hoist gear made it necessary to disconnect the shell scuttle drives from the shell hoist gear; thereafter they were rotated by hand and three extra men added to the mounting crew to operate them.

Summary of modifications in hand or under consideration in 1938

Detail.
  1.  Improved air blast.  (Fitted in Nelson)

  2.  Reintroduction of No1A interlock.  (Fitted in Nelson)

  3.  Solid forgings for traversing tray cross heads.  (Fitted in Nelson)

  4.  Modifications to run-out control arrangements.  (Under consideration)

  5.  Redesign of breech obdurator pads.  (New pads pressed to 8 tons per sq. in and supplied to both ships).

  6.  Modification to depression control gear.  (Fitted in Rodney)

  7.  Modification to elevating gear.  (Gear manufactured, awaiting fitting to both ships)

  8.  Redesign of bogie training arrangements.  (Under consideration)

  9.  Conversion of shell scuttles to hand operation and interlocking gear modified.  (Complete in both ships)

 10.  Modification to control valves of shell room overhead gantries.  (Fitted in Nelson)

 11.  Fitting of interlock to prevent double loading of cordite cage.  (Under consideration)

 12.  Fitting of oil coolers.  (Complete in both ships)

 13.  Modification of pump governors.  (Two fitted in Nelson for trials)

 14.  Cross-connection to run turret pumps in parallel.  (Under consideration)

 15.  Fitting of access doors to cordite hoists above flash doors.  (To be fitted in both ships.

The Early Designs

 The design for the 16" gun mounting fitted to the Nelson class differed in many ways from the initial designs, as more safety features were worked in, and weight savings became more important.  Indeed, many of the later problems experienced with these guns were due to the desire to have as far as possible, a fully automated supply system which was flashtight, made out of the lightest, and therefore sometimes less robust materials.

Some of the major changes during the transition of the design from the "G3" Battlecruisers to the "O3" Battleships that became the Nelson's are as follows;

 1.  The hydraulic mains (normally water in Royal Navy ships), were switched to oil, to allow the use of steel piping as opposed to the heavy duty brass pipes in previous classes.  This gave a reasonable weight saving, and was less costly.  However, the steel pipes were never felt to be as good as the earlier brass ones and seem to have suffered from leaks more frequently.

 2.  The independent shell bogies for each gun were abandoned to save weight and due to the difficulty in co-ordination.  The three fixed position bogies were lighter than three independent ones would have been, but this caused the loading cycle to be slowed considerably.  This was due to the fact that all the guns had to be loaded together, whilst due dispersal problems, it was desirable to fire the wing guns separate from the centre guns in each turret.

 3.  The cordite bogies (similar to the shell bogies) were replaced by cordite hoppers in the final design.  This led to a requirement for more men in the turret crew.

 4.  The supply rate of cordite to the turret also caused problems, as whilst the shells took 35-45 seconds to reach the guns, the cordite took 45-55 seconds to reach the same point.  This was partly due to the greater distance the cordite had to travel, and partly due to the safety interlocks reducing any chance of speeding up the process.  Initially, there was a lesser degree of automation in the mountings, and less interlocks also.  These were added during the design process, as ways of saving weight and reducing manpower became more important, especially after changes 2 and 3 were adopted.

 5.  The roller paths that caused problems in 1928, were 18 inches less in diameter than those for the "G3" design, and indeed the corrective measure of a set of vertical rollers, was already allowed for in the initial designs.  Again, this feature seems to have been changed in an attempt to save weight.

 6.  The turrets for the "G3" design were to weigh 1830-1900 tons (though a figure of 1730 is also quoted, though this seems a little light), whilst those for the Nelson's were 1464-1485 tons.  This difference was due (other than the slightly smaller size of the mounting) to the replacement of various pieces of machinery with the lighter and mostly more fragile versions that later caused so many problems.  It can be seen that in the 1939 Lion design, the turrets are heavier than those of Nelson, whilst having a slightly reduced scale of protection.

These are the major changes to the gun mountings and were certainly the ones that caused most problems for the designers and for the crews once in service.  There were many other changes in the finer details adopted for the "O3" design (Nelson) that have also led to the ships themselves being thought of as sub-standard or badly built.  The most criticism comes from the supposedly poor performance of HMS Rodney during the final stages of the Bismarck chase, and relate to the damage she caused to herself due to the blast effects from the main armament.

One of the two most notable defects was the adoption of aluminium alloys for most of the minor ships fittings, such as kit lockers, mess racks, store cupboards and indeed the fittings holding some items in place, especially with regards to the crews lockers and wash facilities.  These were all shaken up badly by the main armament being fired, and indeed many became loose and some were even thrown around the cabins and mess decks.  Nobody was injured by these unexpected happenings, though many were shocked by the level of destruction that resulted! In WWII, the shortage of aluminium for aircraft production led to the use of heavier metals for such fixtures in ships of the Fiji class onwards, resulting in an additional 100 tons displacement.

The other major fault was the adoption of Douglas fir for the upper deck, instead of the normal teak.  This was deemed acceptable by the designers due to the weight saving, even though the resulting loss of appearance and durability were appreciated.  However, the fir proved to be less acceptable in service, as it proved to be less resistant to the blast effects from the 16" guns.  Indeed, it seems to have surprised many people quite how much the fir was ripped up when the guns were fired over it.  This appears to have occurred on all bearings at low elevations, and from "A" and "B" when firing forwards, even at higher elevations.  The resulting destruction of the decks was viewed with extreme distaste by some senior officers who wanted the ships to be "tight and tidy" at all times, very similar to the Victorian officers who disliked gunnery practice as it caused soot marks and chipped the paintwork!

Neither of these two faults, though very noticeable caused any loss of fighting efficiency whatsoever! With hindsight, as the ships turned out 1500 tons (Nelson) and 1100 tons (Rodney) under the Treaty restrictions, it is a great pity that some of the measures taken to save weight were ever adopted in the first place!

One of the other things noted about Rodney, is that she seemed to wear out quicker than Nelson.  This was largely because Nelson was nearly always used to test modifications and new equipment.  Rodney was fitted second, as and when/if money could be spared.  When WWII broke out, she was already in need of an engine refit.  She was destined to never receive this much needed refit throughout the war, despite her extensive service, as she was looked upon as too valuable a unit to spare from duties for any period of time, if she was still capable of service.  By the time she could be spared, in 1944, there seemed to be little point in sending her for the refit, as the need for her type had largely passed.

The Shells

The following are the specifications for the G3 and N3 designs, and show how the design altered until the 16"/45cal Mark I of the Nelson's was arrived at.  Also, for comparison, I have included the few details that are relevant from the 18" designs for the N3’s.

	Gun	Projectile	Muzzle Velocity
	16.5"/45cal	2,552 lbs.	2,385 fps.
	16.5"/45cal	2,552 lbs.	2,425 fps
	16"/45cal.	2,330 lbs.	@ 2,450 fps.
	16"/45cal.	2,048 lbs.	2,670 fps.
	16"/45cal.	2,048 lbs.	2,575 fps.
	18"/40cal.	3,320 lbs.	2,500 fps.
	18"/40cal.	2,916 lbs.	@ 2,750 fps.
18”/45cal.		2,916lbs	@ 2,900fps.
18”/45cal.		3,350lbs	@ 2,550fps.

With regards to the 16” (and 16.5”) shells, there was considerable discussion as to the relative merits of the high weight – low velocity combination adopted for the 13.5”, 15” and 18” guns already in service, when compared to the low weight – high velocity combination favoured by the German navy. Several sets of trials were carried out, and some of the early ones did favour the latter combination, although faulty shells seem to have distorted the results from the first tests. Later tests proved far from conclusive as to the superiority of the lower weight shells. Sadly, the documentation for the crucial trials, which it appears were conducted between September and October 1920, that led to the adoption of the light weight shell – high velocity gun combination is missing in its entirety, and despite much searching, I have found no author or source that can shed any reliable light upon why this was the chosen solution. All the documentation remaining seems to indicate that the heavier shell produced at least as good a result (and far better at higher angles of impact) as the lighter shells after the initial trials, which were conducted with a batch of shells that did not pass quality testing for acceptability.

When the 18” gun is considered, there are very few details that survive, although it seems likely that power loading for the charges was to have been adopted as standard as well as an auxiliary power source for each mounting from the start. The guns themselves would have been exceptionally powerful weapons, although a formidable blast effect was to have been expected from them. This does not seem to have caused any great concern at the time, and seems to indicate that the superstructure and fitting would have been strengthened to allow for such effects (the results from Furious and General Wolfe using the far less powerful 18” 40cal weapon using supercharges were well known in the service).

There are various other figures from different sources, although they are found less often, and are possibly less reliable.  The greatest difficulty arises in duplication of figures, such as the 18"/45cal firing a 3,600lbs shell at a velocity of 3,600 fps!  Mostly this stems from confusing data for the 18"/40cal mounted on Furious and General Wolfe in 1918.  This gun fired a 3,320 lbs. shell at 2,270 fps (there are notes that suggest that a 3,600lbs shell for bombardment purposes was produced, but details are few).  However, when used for shore bombardment, the gun had supercharges that raised the velocity to 2,400 fps with the same shell.  It was with these normal shells and supercharges that General Wolfe engaged a railroad bridge in Belgium on 28th September 1918 at a range of 36,000 yards, the longest range at which a Royal Navy vessel has fired upon an enemy. The bombardment was ranged from British Army map co-ordinates, and was complimented by air spotting. Several hits were scored upon the bridge, along with some near-misses, and the operation was considered a great success. The gun had performed at least as well as was expected and proved to be very accurate by any standards (the hits on the bridge certainly being the longest ranged hits achieved by any naval gun at the time), certainly given the rudimentary spotting and ranging available at the time.

For much of the above information I have used the following sources;
"The Big Gun" by Peter Hodges.
"British Battleships of World War II" by Alan Raven and John Roberts.
"Battlecruisers" by John Roberts.
"The Grand Fleet" by D.K. Brown.
"Warship Vol 1" article by John Campbell.
"Ships Cover for G3 Class Design" National Maritime Museum.

I must also give thanks to the staff of the National Maritime Museum and the Imperial War Museum in London for their help over the years, as the above subject is somewhat hard to find any exact information without their help!