Dear Dennis:
The best source online for all naval gun info is the Naval Weapons site (
, run by Nathan Okun and company. As far as I know it is the most comprehensive site for naval weapons in general and the best I've ever found regarding naval guns and armour in particular.
But when it comes to specifics (like in your example of the Bismark) individual sites may be more accurate.
Going back to topic, as Nathan Okun relates, the change over from the older 6-inch mount to the newer 6-inch mount caused a weight increase of 20 percent, and the higher rate of fire was accompanied by a loss in reliability.
This mount served as the prototype for the most successful big-gun mount in the US Navy the 8-inch mount on the Des Moines class heavy cruisers. In contrast to the 6-inch mount the 8-inch was one of the most reliable ever built and had 3 times the rate of fire of all previous 8-inch mounts to boot!
Of course this was obtained by a weight increase of 50 percent. So that must be the price one has to pay for the higher rate of fire and greater reliability.
With newer technology we definitely can increase both the rate of fire and training speed of a 155 mm piece, but I think experience will show that we will have to accept both greater weight and higher servo power in order to do so. Such a weapon could not be mounted on smaller combatant vessels.
Simply grafting a 155 mm gun-howitzer onto a ship (like the Germans did with the turret of a PZH-2000) will not create a dual-purpose weapon. One would have to take the land-based weapon as a basis and deliberately develop it into naval DP gun system.
The current US Mk-45 5-inch gun is a good example of a typical naval weapon. One in which (in contrast to European and Russian practice) the rate of fire was kept down (about 20 rpm) in order to maximise reliability and barrel life.
In operation the weapon is fully automatic and autonomous. The only crew needed are the guys who load the ammunition carousel below decks.
My fear is that the USN will lose sight of a cheap, simple weapons' (i.e. a naval gun) virtues and will spec and gold-plate the thing to death (super missile launcher).
Best Regards,
Dusky Lim