Here's an example from (
http://www2.xlibris.com/bookstore/bo...asp?bookid=455). It's a 5" gun similar to guns used on submarines of the period:
"0642- Command to "open fire" given 5"38 cal. Gun crew at stern of vessel, opening range 11,000 yards, deflection 493. Splash short and to right. Range increased to 14,500 and deflection left 5. Splash short and close in deflection. Range increased to 17,500 yards. Splash unobserved-over horizon. Range decreased by 500-yard increments.
0653- Order to "cease fire" given. Twelve rounds expended with no casualties. Several shots appeared close but range too great for accurate spotting."
So 12 rounds in 11-12 minutes. Then later we have:
0723- Command passed to 5-inch crew to "open fire." Range 13,500 yards and deflection 490. Several of our succeeding rounds fell close to target but great difficulty was experienced in spotting all overshots-splashes could not be seen.
0733- Sub [this is the enemy sub] ceased firing after expending 5 to 7 rounds. All shots were short. Sub resumed chase.
0734- We ceased firing after expending 13 rounds-no casualties and apparently no damage inflicted on enemy.
So 13 rounds in 11-12 minutes.
"0736- Our 5-inch again opened fire with range of 13,000 yards. We crossed target and one shot fell very close to sub's hull.
0737- Sub ceased firing and again turned into our wake and took up the chase. We ceased firing at this time after expending eight rounds without casualty."
So 8 rounds in 1-2 minutes. Why the discrepancy? Well we'll investigate that later. The gun is again used:
"0738- Sub again turned broadside to and opened fire for the third time. We immediately returned the fire and crossed the target at 13,500 yards. Two rounds appeared to score close misses. The sub fired approximately eight rounds at us and the closest hit between 500 and 800 yards astern.
0817- The sub ceased firing after our two close misses and immediately headed for the horizon on our port quarter. The total number of rounds fired by the sub was estimated at between 18 and 22.
0818- We ceased fire after expending a total of 38 rounds without casualty-either material or personal. None of our rounds was observed to have scored a certain hit and from all indications the sub retired undamaged."
So 38 rounds in 40-41 minutes.
There are some apparent discrepancies here. Let's examine them.
First, when the order to open fire is given, the gun needs preparing for action. This takes time. Clearly there was an incentive to get the gun firing ASAP (the vessel was taking fire), so this is the fastest that this gun could be fired at this time. We can conclude that 12 rounds in 11-12 minutes is the highest possible rate of fire for the first 12 rounds when using carefully aimed ranged fire with this type of gun.
The next fire is similar - just under one round per minute. We can assume the boat is firing carefully aimed and ranged shots.
When the gun is next fired the gun crew apparently achieve a rate of fire of one round per 7-14 seconds. Either the estimate of the time is wrong or our gun crew are at their most efficient, perhaps using ready-use ammo and firing as quickly as possible - perhaps less-well-aimed in an effort to scare the enemy boat away or in the hopes of getting a lucky hit with volume of fire.
In the final engagement the firing rate drops drastically - to less than one shell per minute. Nothing has changed - the Japanese boat is still engaging and our crew are returning fire.
Now a total of 71 rounds were fired in a minimum of 63 minutes (while the gun crew were under orders to fire). So 53 seconds per round.
If that rate of fire is BS then reality is BS. Also, note that RFB's rate of fire is nearly twice as fast as the above example.