1. Drawn primarily from John Campbell's Naval Weapons of World War II, but also from Dulin & Garzke, various Warship International issues, and additional unpublished material from Nathan Okun.

2. To a certain extent, weight of broadside is an artificial concept, in that it says nothing about shell quality or armor penetration ability, which really determines how much potentially critical damage one can do to a heavily armored opponent. Shooting lots and lots of shells that don't get through the enemy's belt isn't as effective as shooting one shell that goes kaboom in the other guy's magazine. However, broadside weight does give a rough indication of the raw power of the batteries in question.

3. The Italian 15" was an extraordinarily powerful gun, but achieved its performance at the cost of exorbitant barrel wear (barrel life for this weapon was in the neighborhood of 110-130 'effective full charges'; roughly half that of most other nationalities' 15" guns) and reduced accuracy due to wide salvo spreads. All in all, the tradeoffs probably weren't worth it. Campbell states that the muzzle velocity of these weapons could have been reduced 'with advantage.' On the other hand, the Italians may well have rationalized that the additional barrel wear and reduced life was worth it. After all, (as a friend of mine noted to me once) the Italians would hardly ever be operating terribly far from port, meaning that they could afford more frequent barrel changes because of the proximity of good base facilities. To an American designer (or British, for that matter), accepting higher-power ballistics also meant accepting the possibility of maybe needing to change one's barrels in Northeast Tonga, or some other beastly Pacific sandbox in the middle of No Where, which wasn't really a very palatable option. Hence the more conservative ballistics of American heavy ordnance.

4. It should be noted that firing cycle (minimum time between shots at a 'typical' battle range) is calculated at the base loading angle, which for most ships was between 2 and 5 degrees elevation. In a long-range duel, elevation of the gun to a firing angle of 30-40 degrees would account for several seconds more. Iowa's guns elevated at 12 degrees per second; the fastest of the lot. Most elevated at around 6 degrees per second. (It should be noted that Richelieu alone of these seven vessels could be loaded at any angle.)

Without question the gun whose firing cycle I get the most mail on is Yamato's. Here's how I derived it. The U.S. Naval Technical Mission to Japan issued a report on Japanese ordnance which states that Yamato's firing cycle was 1.5 rounds / minute (i.e. 40 seconds) at maximum elevation. Maximum elevation is 50 degrees, and loading is performed at 3 degrees. This means that the barrel must travel through a total of 47 degrees down, be loaded, and travel 47 degrees back up to maximum elevation, for a total of 94 degrees of travel. Her barrels elevated at 8 degrees per second, meaning that 11.75 seconds would be spent in transit, leaving a total of 28.25 seconds (40-11.75) for loading. This is why I put Yamato's cyclic rate at 30 seconds, and not the 40-45 seconds many of my correspondents have stated as being the true figure. This also jibes nicely with John Campbell's figures, which break as follows:

     Open breech: 2.0-2.5 sec
     Move shell loading bogie forward: 3 sec
     Ram shell: 3 sec
     Withdraw rammer & return bogie: 5 sec
     Move rammer to load position: 3 sec
     Ram shell: 3 sec
     Withdraw rammer: 3sec
     Return charge cylinder and rammer: 3 sec
     Close breech: 2 sec
     Recoil & run-out: 2 sec
     Total: 29.5-30.5 seconds

In addition, it needs to be noted that at ranges above 15,000 yards or so, one would not be able to fire at full speed given the need to watch the fall of shot of previous salvos, which might take as long as a minute to reach their destinations. Firing cycles, then, are somewhat misleading in significance for large-caliber weapons such as these.

5. Campbell cites a firing cycle of 30 seconds. Both Dulin & Garzke's "Axis and Neutral Battleships in World War II" and Breyer's works say18-20 seconds, which is quite fast for a weapon of this size. Again, however, note that practical firing cycles may be lower for the reasons cited previously.

6. Arriving at some quantitative value of 'Gun Power' wasn't easy. Here's my general approach:

Assemble sufficient ballistics data to make some armor penetration calculations.
Calculate the armor penetration of the shells in question.
Assign a basic rating to each shell based on its armor penetration.
Assign a second basic rating for the shell's destructive power after it breaches the armor. This is based on shell weight and burster size.
Combine the two into a final shell rating.
Calculate the number of shells the ship in question could fire during the course of a finite chunk of time; five minutes.
Assign a final gunpower rating which takes into account the shell's penetration and explosive power ratings, and the rate-of-fire (ROF) of the guns.

Ballistics Data

I don't have official range tables for the guns in question (although I'm working on it). So I grabbed the next best thing; the ballistic data from Campbell's "Naval Weapons of World War II", which presents data for most of the large-caliber weapons of the war. However, some of it is in meters, some of it in yards, and I wanted it all in yards. So, I used a nifty program called CurveExpert to fit a 3rd-degree polynomial curve to the data points for each individual gun. With the equation for those lines in hand, I was then able to get very accurate values for both the fall angle and velocity values for these shells at any given range. So I calculated these values at increments of 5000 yards, out to a maximum range of 40,000 yards. [Yes, some of these guns can throw a shell to 45,000 yards, but I decided not to go out that far. It's almost impossible to hit anything out there anyway, and I felt that including a 40,000 yard set of figures would be a somewhat artificial.] [Note: King George V can only throw a shell to 35,000 yards; Bismarck only to 39,000 yards, and these values were used as needed] The values I arrived at are presented below:

7. The tradeoffs the Japanese made for these shells don't seem to have been worth it. The only textbook example of an optimal Type-91 hit was an 8" shell that struck the magazine of the U.S. light cruiser Boise during the Battle of Cape Esperance. In this case, rapid flooding prevented a catastrophic detonation of the magazine. Thus, the shell hit, while causing massive damage to Boise, did not achieve the sort of critical damage the Japanese had sacrificed so much for in terms of raw penetrative power in the design of their Type 91 ammunition. Further, it should be noted that the very long fuze delay times in these sorts of shells (necessary for allowing adequate delay if the shell was transiting underwater to the target) had undesirable effects when the shell struck light plating at flat trajectories (such as superstructures). In these cases, Type-91 shells frequently detonated well after the shell had carried through the target ship and was in mid-air on the other side. In a long-range gunnery duel, plunging fire from a Type-91 shell might conceivably pass through the armor deck and then through the bottom of the target ship before detonation -- again, not a trivial hit, but hardly the optimal amount of damage to be expected from a very large caliber shell penetrating to the vitals of the target.