BB Barrel life

[Dreadnought]

An Iowa class 16"/50 cal gun weights (very,very close) to 106.80 tons depending on breech mechanism or not. When lifting such weights and lengths you must be spot on. or "precise"-;)

[Dreadnought]

I assume they would have spare barrels on hand so they could just swap out when a ship came into port? Assuming you had the barrels ready when the ship pulled in, how long would it take to do a swap of all 9 barrels during WWII and get it on its way again? How many ports were capable of doing the swap? Would a BB in the pacific have to travel all the way back to the mainland US, or could it be done in Hawaii or some other island?

*Each serial number, ship, turret and inspector are well recorded in the ships/yards master logs, they are there forever if you know where to look. For the majority of WWII, the battlehips had a drydock or drydocks(mobile floated)by tugs in specific isles of theatre. The USS Wisconsin was one of the last ships "recorded" in a mobile drydock. If a ship took major damage during WWI,WWII ,Korea or other they would come back to the US either East or West coast ports, we have both that are very capable but in those days they wanted the BB's or the CV's back as soon as possible so their class alone dictated what happened first in many drydocks.

[Dreadnought]

1200 round of 16-inch shells seems to be quite a bit of firing at the enemy. ( Dread's recital obviously is well versed in appearance to the novice! :)

The account of the USS Montpilier CL-57 pass down through a "Sailor's Secret Diary" certianly impresses this reader with the rapid fire of the 5 & 6 inch guns during her Pacific Tour.

Did the smaller gun produce less wear on the barrel, therefore have a longer life ?

*Definately the smaller or 5"/38: were built for "mass" destruction, as they were employed upon the majority of ships either in a duel or single role , they found they're way aboard all navy ships thanks to JFK who had witnessed a few missle tests gone wrong in the very early 1960's and he insisted that all USN ships (service combatants) have atleast one of those guns (no matter the caliber 64,72 etc) to be able to defend themselves if all else went wrong. This being an order from a former USN PT boat sailor who was cut in half at sea by a Japanese destroyer in the dark of night, rescued a fellow sailor and many years later became a prominate US President..

[Dreadnought]

The IJN Yamato and Musashi had a problem in that the 18.1" rifles could not be relined. Once the barrel was worn (estimated life 150-200 firings) it had to be fully replaced. The problem was, the Japanese only made one set of barrels for each of the original ships, Yamato, Musashi and Shinano. There were no replacements made for the barrels once they passed their service life.

When the Shinano was converted to a carrier, that freed up the 9 unused barrels, but this was not enough to replace the barrels on the two remaining ships, consequently the guns were not fired often enough for the crews to be as proficient as the should have been. This deficiency was evident in the Battle off Samar, when the Yamato failed to score a single hit on the ships of TF 77.4.3 (Taffy 3).

* There was a passage I read many moons ago that claimed other. I will try to find this and post it that during the closing days of WWII spare barrel liners were indeed found in a cave along the beach.I will look for this in the future.;)

The second part i agree with.

[RustyBattleship]

An Iowa class 16"/50 cal gun weights (very,very close) to 106.80 tons depending on breech mechanism or not. When lifting such weights and lengths you must be spot on. or "precise"-;)

You are quoting the weight in LONG tons (2,240 lbs/ton) that Naval architects and ship engineers use for the displacement of a ship. For simplicity of the non-naval oriented members of this board, I used the STANDARD tons of 2,000 lbs/ton.

Awright. I know the next question. WHY are ships weight (displacement) calculated in LONG tons.

Simple. That's what 35 cubic feet of seawater weighs. So in ballasting or counterflooding, all you need to know is the volume of your tanks and anything divisible by 35 is the tonnage needed for an even keel.

[Dreadnought]

Unfortunately, yes. Six of the nine we brought back from Subic Bay. They were originally intended to rebarrel the New Jersey during her Viet Nam deployment. But politics cut her duty short.


Dick, if not mistaken these would have been the very same barrels transported by barge into the wet well of the LSD Gunston Hall for delivery to Subic.

[Dreadnought]

You are quoting the weight in LONG tons (2,240 lbs/ton) that Naval architects and ship engineers use for the displacement of a ship. For simplicity of the non-naval oriented members of this board, I used the STANDARD tons of 2,000 lbs/ton.

Awright. I know the next question. WHY are ships weight (displacement) calculated in LONG tons.

Simple. That's what 35 cubic feet of seawater weighs. So in ballasting or counterflooding, all you need to know is the volume of your tanks and anything divisible by 35 is the tonnage needed for an even keel.

:));)

[Gun Grape]

Did the smaller gun produce less wear on the barrel, therefore have a longer life

The Mk12 5/38 DP gun, that was used on just about every class of US ship during WW2 had a tube life of approx 4600 rounds.

The 6/47 used on the USS Montpilier had a tube life of 750-1050 rounds, depending on source.

Tube life depends on to many factors to get into. One thing that you must know is that every round fired is not equal to one round when it comes to computing tube life.

Tube life is expressed as the number of the heaviest rounds fired at the largest charge. Firing other round/charge combinations give a percentage less than a whole for barrel life.

A quick example, 6"/42. If you shoot 1 round of AP Mk 35 round with a full charge, then you have fired 1 round for computing barrel life.

If you fire 1 round of AP Mk 35 round with a reduced charge then you have only shot 0.21 of a full round for computing barrel life.

BTW I pulled the ESR data from the Naval Weapons site. A good quick open source for these types of things. I think Rusty has a page or two over there on the Tech board.

As a former artilleryman, I will tell you that computing tube life is a pain in the butt.

[Station 22]

Japanese gunnery in general was poor off Samar, and probably due to a lack or practice. Yamato may actually have outdone some of her less famous fleetmates. Recent analysis of the battle shows she may have scored multiple hits, with her main and secondary guns.

Not ever seen anything to make me believe that she hit anything during the BOS. If you can produce anything else to show otherwise, I'd like to see it. She only fired a total of 75 practice shots in her entire career

* There was a passage I read many moons ago that claimed other. I will try to find this and post it that during the closing days of WWII spare barrel liners were indeed found in a cave along the beach.I will look for this in the future.;)

The second part i agree with.

From what I understand, the barrels could not be relined or if they could, it involved completly reboring the barrel.

[blidgepump]

Computing "tube life" !!

The Mk12 5/38 DP gun, that was used on just about every class of US ship during WW2 had a tube life of approx 4600 rounds.

The 6/47 used on the USS Montpilier had a tube life of 750-1050 rounds, depending on source.

Tube life depends on to many factors to get into. One thing that you must know is that every round fired is not equal to one round when it comes to computing tube life.

Tube life is expressed as the number of the heaviest rounds fired at the largest charge. Firing other round/charge combinations give a percentage less than a whole for barrel life.

A quick example, 6"/42. If you shoot 1 round of AP Mk 35 round with a full charge, then you have fired 1 round for computing barrel life.

If you fire 1 round of AP Mk 35 round with a reduced charge then you have only shot 0.21 of a full round for computing barrel life.

BTW I pulled the ESR data from the Naval Weapons site. A good quick open source for these types of things. I think Rusty has a page or two over there on the Tech board.

As a former artilleryman, I will tell you that computing tube life is a pain in the butt.

Gun grape thank you for the explanation.

Documentation is grueling agreed. Does the responsibility fall to the gunnery captain on each gun?

[RustyBattleship]

Gun grape thank you for the explanation.
Documentation is grueling agreed. Does the responsibility fall to the gunnery captain on each gun?

I believe it does. Each gun captain has to keep a record of how many rounds of which type were fired. The same is true with tanks and the tank commander has a special log book to record the shots.

After a certain number is met, the report is forwarded to the gunnery officer (in the Navy) or the Ordnance Battalion (in the Army). An inspection is done of the barrel and they will decide if it needs replacement or not.

However, on Battleships a very strange thing happens. On each shot of a 16-inch gun, the liner stretches just a tad longer. When half an inch or so is protruding past the end of the muzzle, a special milling machine is attached to the barrel to flush off the end of the liner to the muzzle. Yet barrel life is still viable though the lands and grooves may be a tad larger.

When we reactivated the Battleships in the 1980's, an Ordnance "Tiger Team" came in and drilled a hole through the 7 1/4-inch thick turret top to mount a velocimeter over the center gun. This was used to record the actual muzzle velocity of each shot and determine if any serious degradation of velocity or accuracy resulted from constant firing.

Don't ask me what they found out as I was not in their private loop.

[Dreadnought]

From what I understand, the barrels could not be relined or if they could, it involved completly reboring the barrel.

*Thats is correct, the bore itself was divided into three parts, this helped reduce stress caused by thermal expansion during firing.

When the liner was worn out it could only be removed by machining it out and installing a brand new #1 tube. It was considered so expensive and time consuming that it was thought more practical to just replace the gun itself.
I was correct, nine guns survived WWII, seven were sliced in half and destroyed in 1946 as per disarmamnet agreements between Japan and the US Army. Two guns and assembly parts were later shipped to the US for inspection. All nine along with tools necessary to manufacturing them were found on a beach in various stages of assembly in a cove north of Kamegakubi. They were not treated for corrosion resistance. Found also were several parts (cradles,breechs,upper handling room, lower handling room, balance weights and slides) and a trial mounting to the 18" gun turrets that Shinano would have recieved prior to her alteration into a CV.

[Dreadnought]

Fell in love with this photo. Who says some of us dont have a sense of humor. Free picture anyone?:))

[Stitch]

The Arsenal I mentioned in an earlier post built their quenching pits to take 18.1" Naval gun barrels as that was a size considered for the Montana class.

I understand that 18" rifles were also originally considered for the Iowa-class in the late '30's, but that calculations showed that they would have led to an unacceptably heavier and larger turret than for the 16" rifles. This would have led to a larger hull, which would have put them over the 108' beam width limit for transit through the Panama Canal. IIRC, the projected performance of the 18" rifles wasn't that much greater than the 16" guns as installed on the Iowa's, so the increase in performance wasn't justified by losing the ability to transit the Canal.

[Tiornu]

The 18in shells would have weighed 3850 lbs. Yow!