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Thread: BB Barrel life

  1. #1
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    BB Barrel life

    My question is that from what I have researched that the barrel life of the BB main guns using AP shells was actually very low. If this is accurate and their is know way even during WW2 to quickly change these barrels, how could they maintain a gun line if their barrels wore out so quickly.

    I also researched that during Vietnam that the use of covers over the powder bags greatly extended barrel life.

    I guesse my question is how could we maintain a BB today if the barrels have such a short life span, and how safe are the main guns today being that quite a few rounds have been fired since the last reactivation?

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    Things have changed a lot since WWII, when battleship barrels had a life of 110-395 effective full charges. I think the first major improvement was "Swedish additive."

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    Official Thread Jacker Senior Contributor gunnut's Avatar
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    This never even occured to me until recently, that barrels need to be changed. I understand it was only the liner that was changed. How was that done? Was that a very complicated and time consuming operation?
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    Quote Originally Posted by gunnut View Post
    This never even occured to me until recently, that barrels need to be changed. I understand it was only the liner that was changed. How was that done? Was that a very complicated and time consuming operation?
    The entire barrel had to be removed from the turret and sent back to an Army Arsenal on the East Coast. That Arsenal had the heating pits to heat up the outside of the barrel while filling the liner with Acetone and Dry Ice. The the liner could be pushed out while the main out barrel expanded a bit and the liner was shrunk a bit.

    While keeping the outer barrel hot, a new frozen liner was put in and the entire assembly dunked in a quenching pit. The liner endes were then trimmed off and the breech locking lugs remachined (more of a polishing than a cutting).

    We had to do that to the center barrel of Turret II on New Jersey after she came back from Lebanon as it had a deep erosion pit in the rifling. We believe this was caused during her 1968 reactivation for Viet Nam and that gun was always used for the first "sighting in" shot. Sometimes, that was all that was needed and got used more than the other eight guns.

    In the 1950's the Missouri had all nine barrels replaced in Norfolk. I have the procedures and photos. It was quite a job.
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    Rusty is that in your book?

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    Defense Professional Dreadnought's Avatar
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    From WWII when the gun was introduced it originally had a wear factor of 290 ESR and Nitrated Cellulose was standard propellant. After WWII SPD (Smokeless Powder Diphenylamine) a cooler burning propellant was introduced to prolong the barrel life. By using cooler burning propellant, and a swedish additive (titanium dioxide and wax mixture to coat the powder bags with) the wear factor on the barrel liner was decreased significantly to more like a 4:1 ratio (or four rounds fired for the wear factor of one round) for the AP round and even less wear for the HC round. Later during the 1980's a polyeurathane jacket was added to wrap the bags in which decreased wear even further. When these changes took place the barrel liners service life could then be expressed in FER (Fatigue Equivalent Rounds)They were and still are rated to approximately 1,500 FER per rifle but must be well kept as the barrel liners are chrome plated for approximately 690 inches from the muzzle face. To give you an example of how this worked out consider the Iowas magazine capacity of approximately 1210 rounds for all three turrets, now just one barrel out of nine had the capability of depleating the entire ships magazine and then some provided they were cooled and maintained religiously as GMG's normally did.

    The guns are comprised of a tube, jacket, liner, three hoops, two locking rings, a liner locking ring, the yoke ring and a screw box liner and then you have the Welin breach assemby. As Rusty has mentioned they are assembled using a method of hot and cold (expansion and contraction) construction methods holding extreme tolerances while being assembled and then tested. Once completed in can then enter the inventory for ships issue.
    Last edited by Dreadnought; 17 Jan 10, at 17:08.
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    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?

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    Senior Contributor surfgun's Avatar
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    Surely there must have been extra rifles, as at Pearl Harbor, rifles were promptly as possible were salvaged from the Arizona and Oklahoma (14"ers, for the old WW1 BB's).

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    Defense Professional RustyBattleship's Avatar
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    Quote Originally Posted by shadow01 View Post
    Rusty is that in your book?
    I only mention the replacement of the gun barrel as I could not find any photos of the changeout. Almost all photos and negatives were destroyed by Port Hueneme after the shipyard closed with the exception of some salvaged by Ytlas before the skip loader dumped them in a truck.

    Below is a photo of the nine barrels ready to be installed on Missouri in Norfolk. Remember, each one weighs 118 standard tons.
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    Quote Originally Posted by RustyBattleship View Post
    I only mention the replacement of the gun barrel as I could not find any photos of the changeout.
    Hey cRusty, did you mention in your book about LBNSY cutting up the 16" barrels?

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    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).

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    Defense Professional RustyBattleship's Avatar
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    Quote Originally Posted by Ytlas View Post
    Hey cRusty, did you mention in your book about LBNSY cutting up the 16" barrels?
    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.

    Two barrels went to China Lake Naval Test Station in the Mojave Desert. They are still there and a friend of mine saw one of them alongside the air strip. One was "accidentally" dropped off at the Los Angeles Maritime Museum when the floating crane made a wrong turn.
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    Defense Professional RustyBattleship's Avatar
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    Quote Originally Posted by Station 22 View Post
    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 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.
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    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.

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    Still looking for some closure....

    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 ?

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