bullet drop at 1000 yards, new v fired cases

Discussion in 'Long Range Hunting & Shooting' started by Topshot, Oct 8, 2010.

  1. Topshot

    Topshot Well-Known Member

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    I have been shooting a load of 93 grains of H1000 behind a 300 grain SMK out of my .338 Edge. Primer is CCI 250 magnum.

    I have noticed that loads using "new" Remington brass shoot on average just over 1 MOA lower at 1000 yards than the same load using once fired brass.

    Can anyone come up with an explanation for this?
     
  2. Michael Eichele

    Michael Eichele Well-Known Member

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    I dont know your reloading process such as if you neck size only etc.....But something I have found in the past (at least with chambers that are not tight) is that firing new brass or full length size brass versus neck sized only brass shows a velocity difference.

    Check your loads side by side over a chrony. You may be suprised what you find.
     

  3. Topshot

    Topshot Well-Known Member

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    Mike,
    I us a set of D.E. .338 Edge dies.

    The new brass is run through the FLS die to straighten out the necks and then loaded.

    The once fired and now fireformed brass is sized with the FLS die backed off 3/4 turn prior to loading.
     
  4. Bravo 4

    Bravo 4 Well-Known Member

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    I would say that if everything is the same-powder/ primer/bullet lots and same environmental conditions...compair the weight of the new versus the older brass.
     
  5. davewilson

    davewilson Well-Known Member

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    can i ask what difference in brass weight would have to do with anything?
     
  6. Bravo 4

    Bravo 4 Well-Known Member

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    I have noticed some inconsistency with my Remington Ultra Mag brass. I have weighed some from a new lot and compaired it to the older brass it was replacing and there was enough difference that I would say the newer brass' case walls were thinner. An average of a few grains of water difference confirmed this. This could cause a change in the pressure in the same load, which can change velocity. All is needed for my .338 EDGE to have a different POI of 1moa @ 1000yards is about 40fps. If he were to chrono them and confirm a velocity difference between the two loads...then all I'm saying is the brass could be the culprit.
     
  7. Michael Eichele

    Michael Eichele Well-Known Member

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    Typically heavier brass is thicker. Thicker brass meens less volume. Less volume equals higher pressure. Higher pressure in this context will equal higher velocities. The opposite will happen with lighter brass.
     
  8. Michael Eichele

    Michael Eichele Well-Known Member

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    Wow Bravo, we must have hit the submit button at near;y the same time!
     
  9. Bravo 4

    Bravo 4 Well-Known Member

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    So are you saying I'm a little faster on the trigger...:D

    Well that can work both ways. "You can't miss fast enough!"-I think somebody running around here has that on his handle.
     
  10. davewilson

    davewilson Well-Known Member

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    i won't argue that a different lot of brass will spit bullets out at a little different speed. but, i will guarantee you that a different volumn of internal case capacity will make absolutely no difference in how fast the bullets will go.
    i will also guarantee you a heavier case doesn't necessarily mean a smaller capacity. i've tested this several times and sometimes the heavier cases will hold more powder.
    the bottom line is...small differences in case capacity mean nothing as far as pressure and speed go.
     
  11. Michael Eichele

    Michael Eichele Well-Known Member

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    So Dave,

    If you took a 338 Edge case with a wall thickness so thick that you had the same capacity as a 340 weatherby mag, and stuffed and compressed the same amount of powder in it, the pressure wouldnt go up?

    Interesting.

    It is a widely known fact that old military cases for the 308 were steel and NOT to use traditional load data. They were also thicker which lessened the case capcity and would cause a dangerous condition when loaded traditionaly.
     
  12. davewilson

    davewilson Well-Known Member

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    obviously you can take this to the extreme, but small case volume differences won't make any changes. separate some cases by weight then measure their capacity. you'll find cases that weigh exactly the same, will vary by internal volume and some will surprize you. i know of a hall of fame shooter and other very good shooters that tested this extensively and came to the conclusion it made no difference. i've tested it, although no where near what i would call extensively, and came to the same conclusion.
    weighing cases will give you cases that all weigh the same, nothing else!
     
  13. Michael Eichele

    Michael Eichele Well-Known Member

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    Ok, in some circumstances you are right. Heavier cases dont always meen less volume. You are 100% correct. So lets assume that when I was refering to heavier cases I was refering to the ones that are thicker.

    That said, I have experience the opposite as you. Using top loads in my 338 Edge using one case brand and lot and using the same powder charge with 'thicker' walled cases from a different lot#, I have has sticky bolts and cratered primers along with higher velocities. Going back to the original cases manifested average velocities and no sticky bolt. Granted I dont have a pressure trace but it seems clear to me that there can be differences. Espescially since it happens to other shooters and me with other guns in similar circumstances. Of course like alot of other things, it is relative. If you are not using max loads and the difference can be much less. The closer you get to maximum pressures, the more sensitive things can be problems become compounded due to the 'little things'.

    Call it what you want but there are circumstances where thicker cases can and do cause higher pressures.
     
    Last edited: Oct 9, 2010
  14. davewilson

    davewilson Well-Known Member

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    Michael, i understand what you're saying but i just don't think it's simply a case volume thing.thicker brass can mean a more difficult bullet release. i know, you turn your necks. different brass can have different qualities. a different lot of bullets, the same thing. there are so many variables with this stuff we don't even know them all. i just know small differences in case capacity mean nothing in the bullets MV.
    i talked to a very competitive 1k shooter a couple years ago. he sorted his brass by how consistant they shot speed wise. when he checked the internal volume he was shocked to discover how much they varied.
    again, i understand what you're saying. i just bet something else was causing your higher pressures, not a small change in case volume.