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Perfectionist

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    Effective full charge[edit]
    (Note: The British Army term is usually equivalent full charge)
    Gun barrels naturally experience internal wear when fired, caused by mechanical wear from the projectile moving along the barrel, and thermal and chemical wear from propellant gases. This wear can reduce muzzle velocity and hence range, affect accuracy, produce unstable projectile flight, and, eventually, cause the gun barrel to fail.
    Most guns are capable of firing different types of ammunition with varying charges, and not all of these combinations produce the same firing damage per round fired. The concept of ‘effective full charge’ provides a means of estimating the remaining life of a gun barrel taking into account the varying charges that can be fired from it before it becomes so worn as to be unusable, or no longer safe.[15]
    To illustrate, the round (i.e. the combination of projectile and propelling charge) that produces the most firing damage is assigned an effective full charge (EFC) value of “one”. Other round combinations are assigned lesser values derived from testing and experience.
    If a gun barrel is capable of firing three different round types: round A (EFC = 1); round B (EFC = 0.75); and round C (EFC = 0.25), and if 100 of each round type is fired, then the barrel is said to have fired (100*1.00) + (100*0.75) + (100*0.25) = 200 EFCs.
    If it had previously been determined from testing and experience that this type of barrel has an estimated wear life of 250 EFCs, this specific barrel is at about 80% of its useful life. Plans would be made to order a replacement barrel within the time an additional 50 EFCs were expected to be fired. However the actual decision to retire any specific barrel would be made on examination and measurement of actual wear rather than that predicted by the EFC count.[15]
    In practice a barrel might be replaced before reaching its EFC life, or the limits of wear. In the case of the 15-inch guns fitted to the World War I Marshal Ney-class monitors a gun was generally condemned when wear reached about 0.74 inches at one inch from the start of the rifling. However it was the usual practice to replace guns when their projected remaining life fell below the ship’s normal full outfit of ammunition per gun, which ensured that the entire magazine could be safely fired in action.[16]

     

    yeah u are very much right.. actually i want to know the methods how the EFC is ascertained for a gun that it will last for 250 EFC for example as u quoted. by what methods manufacturer estimates and predicts life of gun in terms of EFC.? like one could be that thy make one prototype nd fire numbr of EFC rounds? or they carryout modelling and simulations to establish the life in EFC??

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