bullet ogive

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Whitetail Hunter, Sep 27, 2004.

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  1. Whitetail Hunter

    Whitetail Hunter Well-Known Member

    May 30, 2003
    I have read a lot of posts on the OAL 300 RUM. There seems to be big difference from about 3.600 to 3.700. Is this because the bullet ogive for a specific grain changes from lot to lot and manufacturer? I would think that factory rifles 300 RUm Sendero SF would all have about the same length to the lands. Give or take .005 one would think. I know that some want the rounds to fit into the magazine and others single feed, but I would think to a group of rifles made by the same manufacturer would be closer in OAL than that. I guess what I really would like to know is everyone here seems to measure OAL but shouldn't we be measuring from the ogive to the base of the shell.
  2. Coyote Hunter

    Coyote Hunter Well-Known Member

    May 1, 2002
    I have always measured from the ogive to the base.
  3. Fiftydriver

    Fiftydriver Official LRH Sponsor

    Jun 12, 2004
    Craig Lange,

    You are correct that the most accurate oal measurement is from the ogive to the base of the case.

    Most bullets, especially HP and SP bullets will vary as much as 0.020" in length and make it very difficult to get an accurate oal measurement if it is taken from nose to case head.

    The tipped bullets are much more consistant but still I have seen variations of close to 0.010" from different nose lengths.

    To be honest, I have yet to see this make any real difference in accuracy as long as the distance from the ogive to the lands is consistant which it generally is quite good with most bullets.

    Your opinion about factory rifles having the same distance from the bolt face to the origins of the lands is not correct in my experience. I have teken alot of factory rifles apart using the actions for custom rifles. Most of these actions are new out of the box Rem 700 ADL rifles and many in the same caliber.

    The throat length can very widely from one rifle to another, sometimes by as much as 0.050" or more.

    The problem lies in the fact that a company like Rem or any other large rifle maker will have dozens of reamers for a given caliber.

    They also will generally get as many chambers reamed with a given reamer as they can before resharpening the reamer to save on overhead.

    Well, a fresh new reamer will cut a different chamber then a reamer that is on it 20th chambering job.

    Also, the folks that do the chambering are not what youwould call custom gunsmiths. They have a quota of rifles to put out in a day and this does not lead to real precise chambering or any other machining for that matter.

    If you get a rifle that was made on a Tuesday morning, you are much more likely to get a better machined rifle then one that was finished just before the closing bell on Friday!

    Headspace will vary from rifle to rifle as well. I have seen many factory rifles with leadspace measurements in the 0.010" range. This is within spec for a factory rifle but still quite loose in my opinion.

    So if you take a quality chamber with headspace in the 0 to 0.001" range and compare that to a 0.010" headspaced rifle, your oal will vary the same amount or more or less depending on the reamer used.

    Reamers are another variable, while they are close, they are not exact, one reamer to another, there are small variations which will also translate into chamber length variations.

    Good Shooting!!

    Kirby Allen(50)
  4. Whitetail Hunter

    Whitetail Hunter Well-Known Member

    May 30, 2003

    I guess I am suprised that the reamers would have that much difference to them to make the chamber vary that much. It is like you said a production rifle. Thanks for the info.
  5. Guest

    Guest Guest

    Very well put! You da man!
  6. sscoyote

    sscoyote Well-Known Member

    Feb 26, 2003
    Whooaahh to dat-- he is certainly becoming just that, aint he. 50-- could u reply to the question i'm about to post in the Bullets, Ballistics thread??
    Oh, i guess that's where we're at-- Jeez i'm lost.

    [ 09-29-2004: Message edited by: sscoyote ]