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308 military vers 308 win com.

mozepermozeper Member Posts: 10 ✭✭
edited August 2004 in Ask the Experts
I have two swedish mauser CG/63 target rifles, I have decided to have one rebarreled to 308.The gunsmith has asked me if i want 308 military or 308 commercial? I did not know there was a differance.

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    HeavyBarrelHeavyBarrel Member Posts: 1,466 ✭✭✭✭✭
    edited November -1
    I can't help you much but I can say his terminology sucks, he should have asked whether you wanted .308win or 7.62NATO
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    heavyironheavyiron Member Posts: 1,421 ✭✭✭
    edited November -1
    Hi mozeper,

    I believe the question your gunsmith asked is largely acedemic at this point in time, because the differences really don't make much of a difference. If I may interpret - What the gunsmith is asking is what headspacing dimension do you want on the rifle. This is the question he should have asked.

    The 308 commercial and 308 military (7.62x51mm) are different because the 308 commercial was released by Winchester several years before the Army standarized the T64E3 as the 7.62MM. Chamber pressure measurements are inconclusive to settle the difference, because SAAMI standards and the government design specifications measured pressure by differnet methods that were not comparable. It has been said that the chamber blueprints for the two cartridges are different.

    The issue is acedemic because nobody makes 7.62MM ammo that won't chamber to the .308 chamber dimensions. Therefore, 7.62MM military will chamber adequately into .308 commerical chambers.

    The headspace on military 7.62mm can and does run long. To compensate for the longer headspace Nato brass is necessary since it is stronger than commercial brass. This is the reason Lake City brass is so popular - It is strong enough to withstand the pressures generated from the longer headspace without rupture and it is reloadable.

    In some 7.62MM rifles the chambers are dimensionally longer (like the Navy Garands with 7.62MM barrels). Thus, using commercial ammo in such a rifle may increase chamber pressure due to different headspacing.

    All the above information is a summary of information from the following link:

    http://www.fulton-armory.com/308.htm

    You may read it yourself.

    Therefore, if you only wish to shoot NATO 7.62mm ammo from the rifle specify the military 308, but if you wish to shoot commercial and 7.62mm specify 308 commercial.



    Regards,

    Heavyiron[8D]
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    Ray BRay B Member Posts: 11,822
    edited November -1
    In addition to chamber measurements, if the light military match bullets are used that have a very short bearing surface, match rifles will have barrels that are .307" or .3075" rather than the standard .308".
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    nononsensenononsense Member Posts: 10,928 ✭✭✭✭
    edited November -1
    Martyn,

    As has been said before, a picture is worth 1,000 words. Here is an iilustration that represents a comparison between the two chambers.

    184333.jpg


    Use the 'search' function up at the upper right of the screen and look for some of the other posts regarding this question. There has been quite a bit of discussion about this.

    Best of luck!
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    mozepermozeper Member Posts: 10 ✭✭
    edited November -1
    Thanks every one, I have decided on the NATO round, it makes the most sense to me. I am thinking of getting a third CG/63 and rebarrel it to 6.5 remington mag. I like to make my range time interesting. Thanks again Mozeper
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    v35v35 Member Posts: 12,710 ✭✭✭
    edited November -1
    Not familiar with the the CG/63 designation but if it is a modification of the 96 you may be overloading the action with the 308.
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    RaoulRaoul Member Posts: 136 ✭✭✭
    edited November -1
    I can give you an example regarding the illustration in Nononesense's posting. I like to shoot Lake City 7.62 Nato in my FAL. If I use the same Lake City 7.62 Nato in my Springfield Armory M1A1 National Match, I have to whack the cocking handle with a rubber mallet to extract the fired case. There is a big difference!
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    Tailgunner1954Tailgunner1954 Member Posts: 7,734 ✭✭
    edited November -1
    Raoul
    You had better check out the specs for a match chamber, I believe you will find that the neck diameter is much smaller in the "match" chamber, and you might be getting into a over-pressure situation with it (your rifle is trying to tell you somthing, listen to it), why wreck a good rifle?.

    Whittemore
    Some guys like a mag full of lead, I still prefer one round to the head.
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    RaoulRaoul Member Posts: 136 ✭✭✭
    edited November -1
    Tailgunner,

    Yeah, I know. I just meant to offer this as a warning not to use 7.62 Nato in a match chamber. It deserves repeating.

    I've even run into this problem occasionally with some commercial ammo in my M1A. With the M1A's tight match chamber, you have to keep it real clean or sometimes even commercial .308 can be sticky.
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