getting different OAL's each round?

Discussion in 'Reloading' started by bigsal5353, Apr 13, 2011.

  1. bigsal5353

    bigsal5353 Well-Known Member

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    Im shooting a 300 wm with berger 190gr vld's.. Using forseter benchrest seater.. use a comparator to measure my rounds and my guns shoots best with an oal of 3.871, my problem is that every time I load a round and measure it... I get a different OAL, anywhere between 3.870 to 3.875...

    Should I measure each round and adjust my die till they all measure the same or should I leave the die set in one spot and leave each round a different length??? sorry if this is a dumb question
     
  2. bigsal5353

    bigsal5353 Well-Known Member

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    i just saw that someone has a similiar post with a 22-250... In my case it is not a compressed load, all of my primers are seated properly... everything on my press is tight.. using a comparator why am I getting different OAL's without moving my die???
     

  3. BuckSnort

    BuckSnort Well-Known Member

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    Are you adjusting the die for depth after each one is seated or have you seated at least two bullets without adjusting the die?
     
  4. bigsal5353

    bigsal5353 Well-Known Member

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    I started out seating with the die in its original place... NOW I'm adjusting the die so that when i measure the length using a comparator I get the same number, I dont know if this is right?
     
  5. retiredcpo

    retiredcpo Well-Known Member

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    I read/heard somewhere on some dies the berger bullets are to long and the dies actually push on the tip not around the bullets which can give a differance in lenght.
    I checked some of the bergers I had when I was loading them and found they varried in lenght up to 040 thou whinc is alot and one of the reasons I stopped using them
    retiredcpo
     
  6. backwoods83

    backwoods83 Well-Known Member

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    Berger has had some issue with the length of the ogive so even if you use a Comp micrometer seater it wouldn't help you need to measure the ogive length and sort them in different batches then when you change batches reset your seater die, I have seen .002"-.006" difference in ogives, hope that helps.
     
  7. Gene

    Gene Well-Known Member

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    Even the very best custom bullets vary somewhat in length. I don't like the comparator for the very reason you cite. I prefer the Davidson base and nose pieces available from Sinclair. The nose piece stops on the ogive, giving very accurate OAL readings.

    With dies equipped with a micrometer top, I like to seat them about .005" or so high. Measure each and set them up in a loading block, mark each line in one thousandths increments. Then lower the mic top one thou at a time to hit the exact OAL right on the mark. If you do not have a seater with mic top, you cannot do this.
     
  8. backwoods83

    backwoods83 Well-Known Member

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    Well that works but if your measuring OAL from tip to case head your gonna be off as much as .005" in either direction, the measurement you should worry about is from the end of the ogive right before the bearing surface to the base, because if one is .005" to long and you adjust to seat it .005" deeper then you just added pressure, doesn't seem like much but you put .005" more bullet in your powder space thus ( higher charge density ).
     
  9. Boss Hoss

    Boss Hoss Well-Known Member

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    The OAL does not mean squat when seating bullets. As stated above OGIVE is the key here. You will need to upgrade your seating die. Better yet use an arbor press and Wilson seating dies.
     
  10. Kevin Thomas

    Kevin Thomas Well-Known Member

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    bigsal5353,

    Boss Hoss is perfectly correct here, the bullets themselves vary a bit in length. This is a natural result of the forming operation and has virtually no effect on how well the bullets shoot. When you're seating a bullet, it's being done (the actual seating) by the forward portion of the ogive, not the tip. The relationship of ogive to leade, or rifling, is what's critical to accuracy. The slight variation in length, which you'll see as variations in OAL from round to round does not play into this relationship. The flip side is, if you painstakingly adjust the die to achieve the exact same OAL on all your rounds, you've now created the variable that you needed to avoid. Make sense?

    Measure some of your bullets, and you'll see what I mean about the variation. Using a comparator, as has already been mentioned, will give you an entirely different view from just measuring the actual length of a bullet. With that done, just seat them normally, check the loaded rounds for ogive positioning via a comparator, and forget about the OAL.
     
  11. bigsal5353

    bigsal5353 Well-Known Member

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    thanks for all that replied.... I understand that I will get varying lengths if I measure from the tip of the bullet.. In my original post I stated that I use a comparator to meaure my rounds and Im still getting variations....

    MY question is: do I let my rounds be off a few thousandths from 3.871 (which is the length I want measuring from the ogive) in either direction, or do I adjust my die each round to make them all match??
     
  12. Broz

    Broz Well-Known Member

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    Bigsal, I have been there. Before I got my new press my seating depth was determined by the amout of pressure and how hard I hit the bottom of the stroke on the press and o-give measurements were different. After I got my T-7 and talked to Redding they told me with the comp. bushing dies I was to adjust the die to a slight cam over of the handle as the die contacts the shell holder. This process has put a reference point for the shell holder to stop at and all ammo is dead nuts the same length. I am not sure what you have for dies or a press as I didn't read the entire thread. Some dies will not allow you to set them to contact the shell holder and will bottom out on the neck of the brass. But if you are using redding bushing dies this is what I would do. One more reason I like my redding dies. Now as long as I set them to cam over I know my die depth is always repeated to the same depth.

    Hope this helps you,

    Jeff
     
  13. sp6x6

    sp6x6 Well-Known Member

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    Bigsal, I just had same problem w/ 338 hyb. and forester die. Turns out the tip vari a little at metplate and that hit my seater first, I DRILLED a small relieve hole in seater, something slightly above 1/8 . Dont recall for sure, did it first on comparator, lokking for problem. Had as much as .005, but I AM much closer now .001- .002 on comp.
     
  14. bigngreen

    bigngreen Well-Known Member

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    I think Broz hit it! I don't bottom out on the shell holder with the seating die I use but I found that I make a very deliberate stroke and hold it firmly for a couple seconds at the bottom that I seat my bullets within .001, if not I easily get .005 of spread in my length.