Sierra bthp seating

Discussion in 'Reloading' started by Texas Republic, Jan 5, 2013.

  1. Texas Republic

    Texas Republic Well-Known Member

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    Aug 27, 2009
    I have a simple question (I hope). I am pretty picky on my reloads.


    I reload a lot of 175 gr. Sierra BTHP for my .308 rifle. The OAL for my load is the normal 2.800".

    However, after seating the bullet my OAL varies to some degree. For example, I seat one that measures spot on at 2.800". The next may be 2.805". The most is 2.808" probably. After measuring the overall length of several bullets, I quickly discovered that the Sierra bullets are not all the same exact length. I realize the ogive is what counts really.

    My question is this. Since the die uses the ogive to press down on the bullet into the brass, should I even worry about slight variations in the OAL? The die should be pushing on the ogive, which is hopefully the exact same spot on every bullet right? So just because one loaded round is slightly longer than another, it doesnt mean the ogive is any different.

    Any clarification on this would be appreciated.
     
  2. Bullet bumper

    Bullet bumper Well-Known Member

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    May 20, 2009
    You are right forget the OAL to the tip of the bullet except for magazine fit and function.
    For bullet seating it means nothing really.
    As long as you seat your bullets to the place you want , that is , off , on or into the lands of the rifling that gives the best accuracy or the type of ammo you want then not much else matters .
    If you are feeding one at a time by hand then magazine fit is not essential either.
    How much bullet tip is sticking up the bore does not matter.
    Bullet comparators measure from the ogive well away from the meplat to the base .
     

  3. tlk

    tlk Well-Known Member

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    Apr 11, 2008
    You are correct. I would like to add one other thing: double check your rounds after they are loaded. You may find that the length as measured at the ogive may vary somewhat. I have a forster comp seating die and notice that they can be a little off depending on other variables such as time between annealing, how inconsistent sizing between the case necks, etc. I have those mistakes addressed and my process improved so that this is not an issue, but it still comes up with at least a few stragglers with every loading session. I have come to the conclusion that it has to do with bullet drag/case neck tension more than anyting else. When everything is consistent it is much less tedious to get where I want to be.

    Since I measure every one of them and adjust those that need it, almost every one of my loaded cartridges will be right where I want them. Had I never bothered to follow up and measure this I would not have found issues in my reloading process.

    Hope this helps.
     
  4. Texas Republic

    Texas Republic Well-Known Member

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    Aug 27, 2009
    Its for a semi DPMS LR308 so I probably need to just make sure the OAL fits in mag. Great....no more measuring OAL after my seating die is set up for 2.80"