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Bullet Comparator?

Discussion in 'Handloading and Reloading' started by KAC1911, Apr 5, 2013.

  1. KAC1911

    KAC1911 Well-Known Member

    Anyone us a bullet comparator?

    I have a older stoney point (believe Sinclair ownes it now) OAL guage and caliper.

    Won't that give me the true OAL when the bullet touches the rifling and then back off seating depth for the most acurate length?
  2. USSR

    USSR Well-Known Member

    Yep. A comparator used in conjunction with the Hornady/Stoney Point O.A.L. Gauge will allow you to set up your bullet seating die to produce ammo with an overall length in which the bullet ogive is a specific distance from the lands.

  3. KAC1911

    KAC1911 Well-Known Member

    Don, are you saying to get a true reading I need to use the comparator too?
  4. cfullgraf

    cfullgraf Well-Known Member

    Bullet comparators measure off the ogive of the bullet. The ogive is supposed to be more uniform than the over all length of the bullet.

    There are other tools/methods that allow you to measure where the rifling lands start. You then use a comparator to ensure your seating depth is as desired.

    Hope that makes sense.
  5. USSR

    USSR Well-Known Member


    I use the hexagonal bullet comparator as sold by Sinclair. You use it as depicted in the picture below. First, you use your Hornady O.A.L. Gauge to determine the seating depth at which your bullet's ogive contacts the lands. Then, you set your seating die to seat the bullet 0.010" shorter if, for example, you want your bullets to be 0.010" off the lands. Hope that helps.


  6. KAC1911

    KAC1911 Well-Known Member

    Thanks guys.

    Don, that was the one I was looking at too. I believe you zero out the comparator too for the actual OAL IIRC.
  7. Walkalong

    Walkalong Moderator

    I use that nut from Sinclair as well. I don't zero out the caliper, I just log whatever the measurement is. I also make a note in the log book how I reached that number. I do the same for getting shoulder measurements. I log what I use to get the measurement.

    Such as:
  8. Bmac1949

    Bmac1949 Well-Known Member

    Question for USSR. What type of seating die are you using to get such a consistent OAL? What I'm using wouldn't allow me to seat the bullet that close. I probably get +/- .003 when I'm seating .270. Measuring from the ogive. Thanks.
  9. USSR

    USSR Well-Known Member


    I use a Redding Competition bullet seating die which has micrometer-type adjustments.


    As Walkalong said, just log whatever the measurement says.

  10. KAC1911

    KAC1911 Well-Known Member

    Thanks again USSR & Walkalong for the help and suggestions for logging info.
  11. fguffey

    fguffey Well-Known Member

    I am the fan of the transfer, the standard and verifying, No Sinclair, no Hornady, no dial caliper, I transfer the chamber dimensions from the chamber to the seating die. Again, I drill the flash hole/primer pocket to a diameter that will accommodate a push rod like a cleaning rod or a gun friendly wood dowel. I simply seat a one of the bullets I am going to load into a case I am loading (with good bullet hold), after seating the bullet I remove the bolt, chamber the transfer, then with a push rod I push the bullet out of the case until it contacts the rifling and stop, After pushing the bullet out I remove the transfer to the press and install the seating die with the ram up.

    The die must be adjusted to crimp and or not crimp, then with the seater plug adjusted/backed out to prevent contact with the bullet and the die secured with the lock ring I adjust the seater plug down until it contacts the bullet. At this point the seating die is adjusted to seat bullets .000” (zero) off the lands. After zeroing it is possible for reloaders that are familiar with depth micromeres, height gages and dial calipers adjust the seater plug to seat the bullet bullet ‘off the lands’ by adjusting the height of the stem above the seater die if they understand the concept of ZERO.

    This method/technique allows the reloader to make one adjustment instead of raising the ram, making an adjustment then lowering the ram, removing the case, measuring, then going back to installing the case in the shell holder and raising the ram and making another adjustment then repeating the procedure again and again etc..

    Bullet hold, I do not want the bullet to move, I want the neck of the case to hold the bullet, I want all the bullet hold I can get, shredding the neck allows the bullet to move with the slightest amount of handling, again, I want a transfer that allows me to transfer the dimensions of the chamber to the seating die. The modified case comes in one size, chambers come in all sizes, when forming cases I off set the length of the chamber with the length of the case, I am not stuck with one size modified case for all chambers.

    Seating off the lands, again, I am the fan of ‘bullet jump’ I am the fan of the ‘running start’ I do not want my bullet setting still at the lands when pressure builds behind it. I do not want my bullet to stop at the lands, there is something about ‘time as a factor’ that causes me to want ‘the running start’.

    F. Guffey
  12. Walkalong

    Walkalong Moderator

    Always more than one way to skin a cat. Interesting approach to measuring where the bullet is in the case when seated at the lands.
  13. thump_rrr

    thump_rrr Well-Known Member

    I mean this with the greatest amount of respect.

    This is one of your more coherent posts.

    I like the methodology you use in reloading.
    Sometimes the way you present it comes off as a little "arrogant" but this one was more factual and directly to the point.
  14. Matt Dillon

    Matt Dillon Well-Known Member

    I Use a Hornady comparator which uses little inserts. I have recently begun loading. .223, so I purchased a .223 insert. I can't. Use it to. Compare. The ogives of .223 bullets, because it is the same diameter as the projectiles. My 30 caliber insert. Works great with 30 caliber projectiles, so what. Size Do I. Need for. .223?
  15. NeuseRvrRat

    NeuseRvrRat Well-Known Member

    the correct insert for the hornady tool for measuring off the ogive of the bullet is stamped "2-22". the hole in the insert will actually measure smaller than the bullet diameter. bullet diameter for .223 Remington is .224". i just did a quick check of my hornady insert and it measured about .215".
  16. Matt Dillon

    Matt Dillon Well-Known Member

    Thanks so very much!

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