Quantcast

Homemade throat/land locating tool?

Discussion in 'Handloading and Reloading' started by ATLDave, Jun 21, 2018.

Thread Status:
Not open for further replies.
  1. ATLDave

    ATLDave Member

    Joined:
    Aug 30, 2011
    Messages:
    8,253
    Sometime in the last year or two, I read an article or post about how to size/prepare a case to accept a bullet with a near-slip-fit. The idea is then to put that case, with a bullet of the type you are developing a load for, but no powder or primer, into the gun for which you are loading. You leave the OAL quite long. Then, when you close the bolt, the ogive of the bullet will bump the rifling and begin sliding back into the case Carefully extract the case and bullet, and measure... that should be the OA length that gets you just on the lands. Set up your dies and adjust from there as desired/prudent.

    Well, now I can't find that article/post. Does anyone here use this method? If so, how do you prepare the case for this use? How do you avoid putting back much neck tension... after all, we're not trying to jam the bullet any distance into the lands... just touch them.

    Any help? Thanks in advance.
     
    .308 Norma likes this.
  2. GBExpat

    GBExpat Member

    Joined:
    Nov 5, 2007
    Messages:
    5,717
    Location:
    Rural, far beyond the beltway, Northern Virginia,
    Use a dremel + thin wheel to cut the neck lengthwise on each side.
     
  3. Ruger 15151

    Ruger 15151 Member

    Joined:
    Dec 4, 2016
    Messages:
    266
    Location:
    Pacific Southwest
    Gottcha and ATLDave like this.
  4. ATLDave

    ATLDave Member

    Joined:
    Aug 30, 2011
    Messages:
    8,253
    NICE! Thanks guys!
     
  5. .308 Norma

    .308 Norma Member

    Joined:
    Jun 6, 2016
    Messages:
    2,006
    Location:
    SE Idaho
    Dave, there’s another method that I prefer. It works best with two people. I’ll try to outline it:

    1. Buy a few 36” long dowels – a quarter inch diameter dowel will work great for 7mm and 30 caliber barrels.

    2. Remove the bolt from your rifle.

    3. Using your little finger, or a short piece of one of the dowels you bought if your finger is not long enough, push the bullet up into the chamber of your rifle until it contacts the lands.

    4. Hold the bullet against the lands while carefully putting a dowel down the rifle’s barrel until the dowel is resting on the tip of the bullet.

    5. Using a sharp pencil, make a mark around the dowel at the end of the rifle’s barrel. Be as precise as you can.

    6. Remove the bullet from the chamber - you might have to give it a gentle nudge with the dowel.

    7. Remove the dowel and re-install the rifle’s bolt.

    8. Put the dowel back down the barrel until it is sitting on the face of the bolt.

    9. Make another mark around the dowel at the end of the rifle’s barrel, again being as precise as you can.

    10. Remove the dowel from the rifle’s barrel and measure the distance between the marks - I use a caliper. The distance between the marks is the OAL for that cartridge, using that bullet, seated so that it is contacting the lands in that rifle. It’s up to you how close to the lands you want to seat your bullets. I personally like a little clearance for my hunting rifles.
     
    horsey300, higgite, LoonWulf and 2 others like this.
  6. ATLDave

    ATLDave Member

    Joined:
    Aug 30, 2011
    Messages:
    8,253
    .308 Norma,

    Thanks, that generally seems logical. Does that method work with secant-ogive bullets? Is there enough self-alignment to get basically the same jam-the-lands length every time with such bullets?
     
    .308 Norma likes this.
  7. .308 Norma

    .308 Norma Member

    Joined:
    Jun 6, 2016
    Messages:
    2,006
    Location:
    SE Idaho
    You got me there Dave. It's going to take me a while to look up what "secant-ogive bullets" are.
    I'll get back to you. Maybe someone else will chime in in the meantime.:)
     
  8. ATLDave

    ATLDave Member

    Joined:
    Aug 30, 2011
    Messages:
    8,253
    .308 Norma likes this.
  9. .308 Norma

    .308 Norma Member

    Joined:
    Jun 6, 2016
    Messages:
    2,006
    Location:
    SE Idaho
    Thanks Dave.:)
    OK, now I know the difference between secant ogive and tangent ogive bullets. Unfortunately, I don't know whether or not my method for finding the OAL for a cartridge with the bullet seated touching the lands will work with secant ogive bullets. I've never gotten into "high-precision/long-range" rifle shooting. I'm a hunter, and the tangent ogive bullets I've always used for hunting are plenty precise at the ranges I've used them.:)
     
    ATLDave likes this.
  10. Blue68f100

    Blue68f100 Member

    Joined:
    May 25, 2011
    Messages:
    5,351
    Location:
    Piney Woods of East Texas
    I've done it this way for decades. Make sure you get all the burrs off, inside and out. The hard part is getting the tension right on the bullet. If you happen to have a bushing die set you may be able to size it for a slip fit.
     
    ATLDave likes this.
  11. edwardware

    edwardware Member

    Joined:
    Feb 23, 2010
    Messages:
    1,907
    The problem is that I want to measure ogive-to-lands contact to within a thou' or two, about 1/20th of your typical sharp pencil line.

    I use a fired case, with just enough neck sizing to grip a bullet. Three repetitions within the requisite 0.002" range confirms you're seeing the actual contact measurement. You should strip the bolt in actions with a sprung extractor, but the fired case reduces that effect.
     
    Gottcha likes this.
  12. 243winxb

    243winxb Member

    Joined:
    Jul 7, 2004
    Messages:
    11,077
    Location:
    Hopewell Big Woods
    Fired case, pliers, pinch neck, making neck oval. insert bullet . chamber. Extract while keeping bullet from hitting receiver. The ejector is pushing it.
     
    ATLDave likes this.
  13. spitballer

    spitballer Member

    Joined:
    Dec 20, 2013
    Messages:
    1,036
    Location:
    Central FL
    IMO GBExpat and 243winXP's methods are sound and mine only differs in that I use a set of neck-sizer bushings to achieve the same result. The only written material on this subject that I've seen personally is in the Lee reloading manual and it doesn't delve into ogives.
     
    ATLDave likes this.
  14. wrench459

    wrench459 Member

    Joined:
    Jul 22, 2017
    Messages:
    188
    I have to set some of my reloads very short due to the ogive.
    This is with a 9mm hand gun.
    I run ~.010-.030 off the lands most of the time just depends.:confused:
     
  15. someguy2800

    someguy2800 Member

    Joined:
    Sep 16, 2015
    Messages:
    5,329
    Location:
    Minnesota
    I’ve been doing it for years by opening up the neck of a sized case with a round chainsaw file until the bullet is a slip fit. Takes 5 minutes. If you get a bullet stuck knock it out with an impact puller. I mark the modified case and keep it in the die box.
     
    Gottcha, .308 Norma and ATLDave like this.
  16. WestKentucky

    WestKentucky Member

    Joined:
    Feb 1, 2014
    Messages:
    8,180
    Location:
    Middle Tn
    Maybe. I tried that but wasn't really successful. The problem is that the expanded neck has essentially no tension if it has any at all. The method of using a sized case with a slit is much more user friendly.
     
    LoonWulf likes this.
  17. jmorris

    jmorris Member

    Joined:
    Sep 30, 2005
    Messages:
    13,936
    Color the bullet with a sharpie or dykem if you have that. Then test & tune until you can see the rifling disturb the color on the bullet.

    If you want to be precise about seating depth, this is pretty easy.



    Generally I am an “off the lands” guy but it does help out on some firearms I have.
     
  18. LoonWulf
    • Contributing Member

    LoonWulf Contributing Member

    Joined:
    Jul 3, 2010
    Messages:
    9,391
    Location:
    Hawaii
    With any method of "push the bullet against the lands" I would suggest smoking (or otherwise coloring), and chambering a dummy round at the oal your inclined to use after you do your push test. That way youll know your out of the rifling.
    Ive found it doesn' take alot of pressure to get a bullet a surprising ways into the rifling.
    I use the cut neck after partial sizing method, you can change tension by just bending the neck halves in or out, and have found that im offten a ways into the lands if I don't reduce the tension a little.
     
    .308 Norma likes this.
  19. ATLDave

    ATLDave Member

    Joined:
    Aug 30, 2011
    Messages:
    8,253
    jmorris, your equipment videos always amaze me.
     
  20. ATLDave

    ATLDave Member

    Joined:
    Aug 30, 2011
    Messages:
    8,253
    Just to be clear, I'm not necessarily trying to ultimately seat into the lands, just get a reference point for where the lands are and how far "off" them I will be.

    I've never messed with this before, but I've never been loading for a 6.5-06' set up for long distance benched stuff, either!
     
  21. Nature Boy

    Nature Boy Member

    Joined:
    Apr 21, 2015
    Messages:
    4,472
    Me too
     
  22. Tilos

    Tilos Member

    Joined:
    Jan 13, 2010
    Messages:
    1,320
    You can cut the dowel to a length less than 6" longer than when placed in the barrel touching the bolt face.
    Then you can measure what's sticking out with your caliper, instead of marking the dowel.
    :D
    Edit: for an auto:
    An easy method to determine OAL can be done using a Digital or Dial Caliper and a new pencil cut about one inch longer than the barrel.

    With the barrel removed, put just a bullet into the chamber until it stops and hold it there.
    Now put the cut pencil into the muzzle until it touches the bullet nose and measure the amount of pencil sticking out of the barrel.
    Use the step feature on the BACK of the caliper and note the measurement.

    Remove the bullet and re-assemble the barrel/gun.
    Now put that same pencil into the muzzle until it touches the breech face and again measure the amount of pencil sticking out of the barrel.

    The difference between the two measurements is the MAXIMUM overall length that will CHAMBER in THIS barrel/gun/bullet combination.
    Use the back of the caliper like this to measure:
    RCBSpowder.JPG
     
    Last edited: Jun 23, 2018
    .308 Norma likes this.
  23. berettaprofessor

    berettaprofessor Member

    Joined:
    Mar 25, 2008
    Messages:
    2,549
    Location:
    Kansas
    Uhmmm doesn’t anybody else use an OAL caliper like Hornadys? I used a split case once or twice before but if you want to accurately measure to the lands, get a gauge made for it.

    Addendum; I see the OP was asking about homemade...but there are times to pay for good equipment and this is one I think.
     
    Allen One1 likes this.
  24. higgite

    higgite Member

    Joined:
    Dec 17, 2009
    Messages:
    1,146
    You can also score the dowel with a razor blade for a more precise measurement.
     
    horsey300 likes this.
  25. jmorris

    jmorris Member

    Joined:
    Sep 30, 2005
    Messages:
    13,936
    Like this one?

    C460342F-A843-4824-B73B-9367B8A09538.jpeg

    You don’t need to spend much money to duplicate the device but it’s even cheaper and just as accurate to use some of the methods mentioned in this thread.

    Worth pointing out that this dimension can vary quite a bit sometimes, when seating to the lands.

    507B2264-7751-4318-A0C5-6AF3EDFB8FE9.jpeg

    This is a more consistent way to measure the area of contact as tip inconsistency doesn’t effect readings.

    341594BE-C158-40E8-B9A3-64468F1F3A87.jpeg
     
    Last edited: Jun 22, 2018
Thread Status:
Not open for further replies.
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice