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Thread: Changing brass

  1. #1

    Changing brass

    Hi,

    I have just brought some new brass and changing from Nosler to Norma in 204.

    Do I need to retest rounds with increments on powder weights due to brass change, surely the brass is all Sami spec and should not need me to retest?

    i was thinking of trying a .2gr lower than my usual load and my usual load to see what's happening!
    Last edited by foxyrich; 14-08-2014 at 21:12.

  2. #2
    Cases vary in thickness and volume,
    best recheck as pressures can be significantly different especially if you are hot already

    just done this with a rem to Norma change
    took me a while to find some 300wm Norma brass now it seems to be everywhere!

  3. #3
    SD Regular
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    A simple rule of thumb is that you should weigh the new brass as against the brass you worked up your loads in. If it is heavier it will have a reduced capacity. You should also trim the new brass to the same OAL as the brass you worked up your loads in.

    Both of these are the two most likely factors to affect pressure. But also will be the thickness of the case neck as against that of the brass you worked you loads up in. Now to complicate matters some "other makers" brass is, in fact, made by Norma!

    So Nosler brass may be Norma or it may be made by others instead. Some may know as maybe will Nosler.

    BUT AS A RULE OF THUMB ANY COMPONENT CHANGE FROM THE ORIGINAL RECIPE REQUIRES A 5% REDUCTION FROM THE LOAD YOU WORKED UP USING THE ORIGINAL THREE COMPONENTS, BRASS, PRIMER, BULLET.

    SO NO, IMHO, .2 OF A GRAIN UNLESS THAT IS 5% IS NOT ENOUGH REDUCTION OR UNLESS THESE ARE MEDIUM POWER PISTOL OR REVOLVER CARTRIDGES YOU ARE LOADING....

    SAAMI "SPEC" APPLIES TO OUTSIDE DIMENSIONS ONLY AND NOT INTERNAL CASE CAPACITIES.
    Last edited by enfieldspares; 14-08-2014 at 21:38.

  4. #4
    Norma make an awful lot of brass for other people.
    but it is not the same constituents or made to the same requirements.


  5. #5
    there is another picture but I can't find it
    brands include Nosler, Lapua, Weatherby, RWS, Sako, etc etc

  6. #6
    I would say check even different batches of Lapua can have different capacities.

    In my case with 24 grn Varget in .223 some are approx 95% full other batch is compressed and I have to adjust my seating die as in compressed bullet needs a bit more pressure to seat it. at correct COL.

    They also shoot different POI best check and see what occurs in your situation

    D

  7. #7
    If you don't wish to follow the time tested guidelines mentioned above you can do this: Weigh a sample batch of each makers brass after the cases have been FL resized and identically prepped. (trim, cleaned,primer pockets uniformed if you do such things) Take the average weight of the samples. If the new brass is lighter, carry on. If it's heavier, reduce the charge weight by 12% of the difference in weight.

    It's always better to reduce charges and begin anew.~Muir

  8. #8
    Quote Originally Posted by Cyres View Post
    I would say check even different batches of Lapua can have different capacities.

    In my case with 24 grn Varget in .223 some are approx 95% full other batch is compressed and I have to adjust my seating die as in compressed bullet needs a bit more pressure to seat it. at correct COL.

    They also shoot different POI best check and see what occurs in your situation

    D
    D. Have you tried using a drop tube when filling the cases? Using the drop tube, the kernels pack better and the compression on seating is less.

    https://dl.dropboxusercontent.com/u/...ing%20good.jpg

    Regards JCS
    Last edited by jcampbellsmith; 15-08-2014 at 12:30.

  9. #9
    Checking cases by weight alone is inaccurate, the extra weight may be in the base and have no effect on the internal volume which is the important factor, as someone pointed out earlier batches from the same manufactuer can vary, best way is to seat a used primer the wrong way round, weigh the case, zero your scales then fill the case with water and re weigh the case. This will give you the internal volume in H2O

  10. #10
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    ...the extra weight may be in the base and have no effect on the internal volume...
    Eh? How that's work then?

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