just curious

Discussion in 'Reloading' started by rclouse79, Oct 14, 2010.

  1. rclouse79

    rclouse79 Member

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    Apr 12, 2010
    Part of the fun of starting to reload is trying to figure out why things are the way they are. According to my measurements using the hornaday oal gauge and bullet comparator the shortest jump to the lands I can achieve with a barnes 130 grain ttsx while still fitting in the magazine is .010. With a 130 grain nosler accubond the shortest jump to the lands while still fitting the magazine is 0.075. I decided to take some measurements on each bullet and in an attempt to understand the differences between the two.
    Bullet length (ttsx- 1.324, acc – 1.241)
    Comparative Bullet length using hornaday bullet comparator (ttsx – 1.785, acc – 1.702)
    The actual bullet comparator that attaches to the calipers is 1.002. By subtracting that number from the comparative bullet length I figured that would give me the distance from the base of the bullet to the ogive. (ttsx-0.783, acc- 0.700)
    By subtracting the length found above from the bullet length I figured I would get the distance from the tip to the ogive. (ttsx-.541, acc- .541)

    I am thinking I did something wrong or had a misconception along the way. It seems to me that if both bullets actually have the same distance from the ogive to the tip they should be able to achieve the same jump to the lands while just fitting the magazine.
     
  2. Mikecr

    Mikecr Well-Known Member

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    Aug 10, 2003
    The tip doesn’t have anything to do with it.

    How did you get this? This OAL ‘stick’ presses against the back of a bullet through a modified case right?

    The TTSX is merely .083 longer from that stick/bullet base to the ogive.
    But your seating depth, set by your seating die, will still be the same distance from the lands with either bullet because the datum here(ogive) is independent of bullet length. The only difference is that the TTSX will be seated deeper in the neck.
    You will still need to determine best OAL to ogive, and I wouldn’t bother with one of them sticks. Pick up a Sinclair ‘NUT’ and measure it with calipers.
     

  3. kiwi3006

    kiwi3006 Well-Known Member

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    Aug 1, 2007
    rclouse79 - the maths you did on the numbers you posted look right.
    I agree that if the tip - ogive length is the same then they should have the same jump to the rifling if seated to mag length ie base of cartridge to tip of bullet is identical.

    I have never used the Hornady tool but have heard that you have to get the "feel" right, repeat a number of times and average results.

    Don't know if I have helped at all.

    Stu.