bullet comparator?

Discussion in 'Reloading' started by carverelli, Oct 24, 2005.

  1. carverelli

    carverelli Active Member

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    I've got a ? for the experienced vld hp loader. Is it critical for accuracy to have all your loaded rounds at the same oal or is it good enough to seat them usoing the same setting on my bullet seater. I'm loading 6mm 107gr SMK w/ a Redding competition micrometer seater and I'm getting oal variations of .020 or more from different bullets in the same box. I 've seen in Sinclair a bullet comparator that looks like a big hex nut w/ holes in it. I guess you insert the loaded round in it and measure from the top of the nut to the case base. Is this measurement more important for accuracy that oal? As always I appreciate the knowledge from thoses of you that have been there and done that.
     
  2. 270WSM

    270WSM Active Member

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    I use a stoney point bullet comparator that measures the cartridge base to bullet ogive. I also seat my bullets long, take a measurement, and work down to the desired length. I was noticing differences in OAL even when measuring off of the bullet ogive, so I started to seat the bullets this way. I don't know if it's imperative or not. Hope this helps. I'm sure someone else with more experience than I will chime in.
     

  3. wapiti13

    wapiti13 Well-Known Member

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    The more consistent you have your bullet set off the lands, should add to better accuracy. Every bullet wants to be set off to a different spec, but only using a comparator off the bullets ogive will be consistent. OAL just has too much error since any excess length during manufacturing has to go to the point. The ogive is consistent during the manufacturing process. Also, upon firing the ogive is what actually first contacts the lands. Accuracy, pressure, etc. can all vary if contact is not consistent. /ubbthreads/images/graemlins/smile.gif
     
  4. daj

    daj Active Member

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    I do the same as 270WSM - seat long and work down to the desired length. Slightly compressed loads and seating to the lands mean I don't have much choice.

    Regarding varying comparator measurements after seating, differences in neck tension can cause different amounts of spring-back in the shoulder when the seating die is raised.
     
  5. SamSpade

    SamSpade Well-Known Member

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  6. Gun5tuff

    Gun5tuff Member

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    [ QUOTE ]
    I've got a ? for the experienced vld hp loader. Is it critical for accuracy to have all your loaded rounds at the same oal or is it good enough to seat them usoing the same setting on my bullet seater. I'm loading 6mm 107gr SMK w/ a Redding competition micrometer seater and I'm getting oal variations of .020 or more from different bullets in the same box. I 've seen in Sinclair a bullet comparator that looks like a big hex nut w/ holes in it. I guess you insert the loaded round in it and measure from the top of the nut to the case base. Is this measurement more important for accuracy that oal? As always I appreciate the knowledge from thoses of you that have been there and done that.

    [/ QUOTE ]
    I use the Sinclair comparator and you are correct in how it is used. It is a very inexpensive but accurate way of measuring the distance from the ogive to the base of the bullet.

    Peter
     
  7. jb1000br

    jb1000br Well-Known Member

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    The Redding Instant Indicator is a great tool. Though caliber specific, it does several things, and is worth having!

    JB
     
  8. Jimm

    Jimm Writers Guild

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    Sinclair , remember that it is just a comparison , find a tool , use it , record the changes , go from there . I use a Sinclair comp. and the thing is that "the nut" holding the wheel can be a major influence in this matter.

    Jim B.
     
  9. BountyHunter

    BountyHunter Writers Guild

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    I use the sinclair tool 04-900 to measure the lands and the stony point comparators to actually measure the loaded bullets and the other stoney pt gauges to measure the datum line on the shoulder to set up the dies for shoulder bump.

    BH
     
  10. royinidaho

    royinidaho Writers Guild

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    Made one of my own LRH Link

    The funny thing is the SMKs shoot 1MOA+ @200 and the ones w/larger BS variance shoot in the 0.3MOA range @ 200. Also that is with random bullet selection from the box. /ubbthreads/images/graemlins/confused.gif
     
  11. Guest

    Guest Guest

    [ QUOTE ]
    <font color="red">wapiti13: The more consistent you have your bullet set off the lands, should add to better accuracy. Every bullet wants to be set off to a different spec, but only using a comparator off the bullets ogive will be consistent. OAL just has too much error since any excess length during manufacturing has to go to the point. The ogive is consistent during the manufacturing process. Also, upon firing the ogive is what actually first contacts the lands. Accuracy, pressure, etc. can all vary if contact is not consistent. </font>

    [/ QUOTE ]

    <font color="blue">Yap...My thoughts exactly </font>