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.308 brass with military headstamp question..

SwanKongSwanKong Member Posts: 989 ✭✭✭✭
I have 50 .308 brass with a the headstamp RA 64. My question is can I load this the same as I would brass stamped with .308 Win.? Does it have thicker case walls therefore a different case capacity?, which would mean different data?..

Comments

  • bpostbpost Member Posts: 31,137 ✭✭✭✭
    edited November -1
    Any time you switch brass or other components you should back off your load and work back up looking for signs of pressure.

    You will also have to remove the crimp left after decapping the spent primer.
  • charliemeyer007charliemeyer007 Member Posts: 7,348 ✭✭✭
    edited November -1
    Its a lot easier for me to work up lots of 200 rounds of brass at a time.

    The old Win SuperSpeed was thinner brass (one of my fav's). Full case loads of slow powder were sort of self adgusting, less than full case with faster powder can cause problems.

    All the data I ever see lists every componet: case, powder, primer bullet OAL etc for a reason. Always wise to back off some if you change things
  • nononsensenononsense Member, Moderator Posts: 10,642 ******
    edited November -1
    SwanKong,

    The simple answer is to fill one of those cases with water and weigh it. Weigh an empty case and subtract. Do the same with a commercial case and compare.

    You can also section one of these and a commercial case which will allow you to measure the variations in case wall thickness.

    Best.
  • MobuckMobuck Member Posts: 11,548 ✭✭✭
    edited November -1
    Most manuals recommend reducing the load for military cases by 10%. I use a lot of LC brass and velocity results confirm that it takes 5% less powder to reach similar velocities with LC vs commercial(Rem/Win/FC) brass.
    Even switching to European made brass may result in significant pressure variances. I found that a starting load listed for domestic 8x57 brass gave flattened primers and max load velocity when loaded in xyz brand(made in eastern Europe)brass.
    ALWAYS err on the side of safety and work up.
  • SwanKongSwanKong Member Posts: 989 ✭✭✭✭
    edited November -1
    Thanks for the input. I have data in Hornady's book for 308 service rifle but no data for the 180 gr. SST's I would like to use...only target bullets are listed..Working up has been mentioned, but work up form where?..a normal 308 starting load?..
  • Rocky RaabRocky Raab Member Posts: 11,031 ✭✭✭✭
    edited November -1
    If you already have a load for that bullet using commercial brass, you can follow this surefire method:

    Reduce the "pet" load by 5% using all your old components. Fire and chronograph. (You'll get a bit less speed due to the reduced pressure.)

    Now shoot that same 5% reduced load in the new brass (NO other component changes!) and chrono it.

    If the velocity is the same with both old and new brass, you can go back to your favorite load with no other testing required.

    If the velocity is LOWER with the new brass, you can work up to the original velocity level.

    If the velocity is HIGHER with the new brass - but lower than your original "pet" load got - you can work up to the original.

    If the velocity is HIGHER than even the original "pet" load, you have a serious problem with the new brass. Consider tossing it. But at least you only wasted a few shots worth of components.
    I may be a bit crazy - but I didn't drive myself.
  • Okie743Okie743 Member Posts: 1,975 ✭✭✭
    edited November -1
    mobuck said to reduce the charges (for military brass) by 10% starting, this includes the starting load.

    You can also add water and weigh, then add water to a standard brass case and weigh and compare the percentage difference. Military brass is usually lots heavier than standard brass when weighed on a scale, the brass walls are thciker and LESS volume inside, therefore same amount of powder in a military case as compared to a standard brass case will produce more pressure/velocity therefore reduce the power charge by the percentage difference.

    When I have military brass and a very accurate rifle I first work up a accuracy load with standard brass, then later I separate the military brass by weight into about 10% weight piles, then take the majority that are close to same weight, with-in 5 grains then start testing for accuracy using the 10% reduced powder charge and watching the velocity thru a chronopgraph and the on target results.
    I usually end up using the military brass labeled as practice/scope setting rounds, separated from my mail hunting brass.

    If a gun is real touchy for accuracy vs a powder charge, mixing military brass and standard brass can make a very good accurate shooting rifle look real bad on paper for accuracy point of impact! I've seen groups shift by as much as 3 inchs at 100 yards mixing military brass and standard brass with the same powder charge. (not paying attention to the volume/charge of powder reduction or separating the brass per weight)
  • cbyerlycbyerly Member Posts: 703 ✭✭
    edited November -1
    There is a considerable difference between 308 NATO ammo fired in machine guns and semi auto rifles. The machine gun chambers are rather huge compared to rifle chambers. They are difficult to size and will only last a couple of loadings.
  • Okie743Okie743 Member Posts: 1,975 ✭✭✭
    edited November -1
    quote:Originally posted by cbyerly
    There is a considerable difference between 308 NATO ammo fired in machine guns and semi auto rifles. The machine gun chambers are rather huge compared to rifle chambers. They are difficult to size and will only last a couple of loadings.


    I did not know that about the huge chambers!!!!! I ran into some of the military brass that was very hard to re-size and suspected been fired oversized chambers!
  • 11b6r11b6r Member Posts: 16,725
    edited November -1
    I would point out that you do NOT have military .308 brass- you have military 7.62 NATO brass.

    While the external dimensions are the same, the NATO was loaded for lower pressures that the .308, AND military brass is thicker. This means the internal volume of a case is less. Use civilian .308 load data in a NATO case, your pressures are going to be higher than expected.

    As the man said, back off the starting load by 10%.
  • fire for effectfire for effect Member Posts: 121 ✭✭✭
    edited November -1
    The 12 Percent Rule.

    NRA's Formula for reloading Military Brass. Weigh the Military Brass. Then weigh the Comercial Brass. Commercial Brass is thinner so it weighs less. Subtract the weight of the commercial brass from the Military Brass. Multiply the result by 12 percent. this is the amount you reduce your load by.

    example:

    Military case weighs 184 Grains
    Commercial case weighs 175 grains.
    184 - 175 = 9
    9 X .12 = 1.08 grains.

    Reduce your load by 1.08 grains.
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