Do you seat your bullet to OAL or ogive length

Discussion in 'Reloading' started by Scottf, Feb 14, 2010.

  1. Scottf

    Scottf Well-Known Member

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    I am getting into reloading and would like to know is it better to seal the bullet to an OAL or ogive length and why? Is it necessary to sort the bullets? Primary use will be for shooting holes in paper and varmint shooing.
     
  2. BountyHunter

    BountyHunter Writers Guild

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    You may not be asking the right question.

    If it is a magazine gun, you normally do not have a choice.

    You are limited to max magazine COAL.

    If it is a single shot, you CAN go out to touching or even in the lands. This is normally measured off the ogive where it touches the lands.

    In that case OAL has nothing to do with it and you use where the ogive touches as the key measurement with a comparator.

    you will find down the road, that measuring off the ogive (where the bullet touches) is the more uniform measurement.

    If you sort bullets with base to ogive and then measure the same bullets OAL, you can find as much as .017 variance in OAL or more.

    BH
     

  3. boomtube

    boomtube Well-Known Member

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    Most bullet noses vary too much for precise control of seating depth. But, in my rifles, I've found it's the seating depth range that's most helpfull, and that's often as much as .010" wide, not a specific point +/- nothing. Since learning that I develop my loads by the ogive readings but then load in the middle of the window by simply seating to the nose, OAL, because a few thou one way or the other doesn't matter at all.

    For a variety of reasons, weighing commercial bullets is, IMHO, a waste of time. And it isn't needed with custom bullets so it's a waste of time. ??
     
  4. freebird63

    freebird63 Well-Known Member

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    You will have to excuse my stupidity, but I went out and shot my 300RUM today for the first time, I was shooting facotry remington loads with the 180gr Scirroco's. They shot pretty good. Came home and figure I would see if I get get started on setting up a load with my bergers. At first I tried to seat my bullets to the max length, 3.600, well they would not seat. I am wondering if it was the O-give that was causing my rounds not to chamber???? I am going to be shooting 185gr bergers. Can anyone tell me if there is something here I am missing?????
     
  5. johnnyk

    johnnyk Well-Known Member

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    Sounds like the resizing operation didn't go as it should have. Will the bolt close on a resized case without the powder/bullet? JohnnyK.
     
  6. freebird63

    freebird63 Well-Known Member

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    Yes it would close with just the case in the action, but just the minute I seat a bullet in the case it won't close.
     
  7. Ma_Bell

    Ma_Bell New Member

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    Okay,I have a question. I'm an avid shooter an just getting started in reloading. I have a Savage 10FLCP-K chambered in .308 with a 1 in 10 twist. I'm trying to determine OAL using a marker and coloring the bullet. I have a fired, unsized case trimmed to 2.005. When I chamber a round in the case (either a hornady A-max or nosler Accu-Bond) the OAL I get is in the 2.88-2.91 range. Way over the SAAMI max of 2.81. Now, I realize that i'm measuring to to the bullet tip, not the ogive. I realize this isn't the most accurate method, however fitting in the magazine is not an issue. My magazine has enough clearance for more than 2.95. It seems like if I took these measurements (I lan on seating about .010 off the lands) the round would barely be seated in the case. What am I doing wrong? Advice?gun)
     
  8. Mikecr

    Mikecr Well-Known Member

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    I log OALtoOGV for every cartridge, and have never had an issue with consistant seating to those parameters.
    For my measurements, I use a Sinclair comparator(the NUT) and a caliper. After trying many other methods, this is what I came to as being most reliable.
    I doubt it tells me actual distance from the lands, but that doesn't matter. I tweak seating using the nut. I log results OALtoOGV, and this is always given(on my bench) as a reference for most accurate seated measurement.

    IMO, pick your best standard and stick with it across the board.

    As far as seating depth accuracy being important,, I can tell you that I have barrels where it is critical for accuracy. With one(a Cooper/Wilson barrel), 3thou off from optimum means 1/4moa at 300 opens to an ugly 1/2moa. So I care about seating accuracy.
    Luckily, Wilson dies produce no issue here.

    Oh yeah, I should qualify, my guns are single shot, and I use relatively light neck tension(no more than needed).
     
    Last edited: Mar 6, 2010
  9. Moman

    Moman Well-Known Member

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    Assuming you are using a 150 Accubond, which measures 1.230 in length. If you were to seat this in your 2.005 trimmed case, at the OAL of 2.910, you would have .905 of bullet mass outside of your case, with .325 of bullet shank inside your case. It sounds like you have a bit of freebore in your setup. Not a real big deal though.

    I would seat the bullet a little deeper regardless of what your magazine length is. Try seating so that the junture of the shank and boat tail are lined up with the juncture of the neck and shoulder of your case and see what OAL this gives you.

    By the way, welcome to LRH.
     
  10. Fitch

    Fitch Well-Known Member

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    First, and most important, if you don't develope the load with the bullet touching the lands, you don't want the bullet to ever touch the lands. This is becuause having the bullet touch the lands increases peak pressure by something between 6,500 and 7,500 psi, or more. That means backing off the lands enough so that the variation in bullet shape, between bullets intended to be the same, won't cause the ogive to touch the lands. Ever.

    I've never seem as much as .020" variation in base to ogive measurement so I generally seat loads to put the ogive on a "nominal" bullet 0.020" off the lands. I generally measure 20 or 30 bullets from a new box, get an average, then look for an "average bullet", use that to adjust the seating die so the ogive of the average bullet will be about 0.020" off the lands.

    Second, folks who load for a bullet "just touching" are generally kidding themselves. There may be special circumstances but I've never seen a lot of bullets that could be reliabily seated to "just" touch the lands. Seating to just touch will result in some being jammed, some not touching at all. The statistics on bullet geometry don't work for loading just touching.

    Third, jammed into the lands is the most repeatable but not the most desirable on anything but a target rifle. It is quite common to unload a hunting rifle not having fired a shot. Bullets jammed into the lands can stick there resulting in the bullet being pulled dumping the powder charge into the action when the round is unloaded. Having a powder charge d umped into the action is "not" a feature.

    Most rifles will shoot quite well, better than most shooters, with the bullets seated about 0.020" off the lands if the magazine length permits it. That's where I start.

    I will be trying some Berger VLD hunting bullets this summer for the first time. I read their directions on how far off the lands to seat and will follow them.

    Finally, I've tried about every tool out there for measuring chambers to decide how to seat the bullet for that chamber. So far the best tool I've found is the Sinclair tool that is a piece of precision ground rod with two sliding collars on it. It gives me the most repeatable measurements.

    Fitch
     
  11. woods

    woods Well-Known Member

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    Can't disagree with a word of that.

    freebird, most of the time when you can chamber a sized case but can not chamber it after seating the bullet it is one of two things: bullet seated too far out or seating die set down too far so that it overcrimps and causes a bulge. If you are sure you are not into the lands then back your seating die back up a couple of turns, relock it down and then back the seating stem down to where you are again seating to the depth you want.
     
  12. Mike6158

    Mike6158 Well-Known Member

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    How are you measuring seating depth now?

    Sounds to me like the bullet is being jammed into the lands, ie, the cartridge is too long...
     
  13. Mikecr

    Mikecr Well-Known Member

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    I couldn't disagree more..
    -For one, base to ogive variance has nothing to do with seated distance to lands.
    -Second, best seating depth is always where you barrel tells you is best, given your specific components and load. And nobody walking this Earth can predict it.
    -Third, any seating distance desired is quite easily verified by measuring your loaded ammo. This is not an abstract,, it's what you do. You make it right.
     
  14. Fitch

    Fitch Well-Known Member

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    We can agree to disagree. :) But I will explain what's behind my comment so you can help me understand where I'm not understanding this correctly.

    The bullet is only so long. My thinking is that when the distance from the base increases, the distance from the tip decreases. That means the seating die will position the ogive contact location closer to the lands unless it only contacts the bullet at the same diameter the lands would. I don't know any way to adjust the seating die to seat only with contact where the bullet will contact the lands which is the only way a die will give the same cartridge base to ogive contact distance. And if I could get the die to push there, I'm not sure that is a good idea.

    If you have a way to have the seating stem push on the bullet at the land/ogive contact ring with out damaging the bullet, I'll give it a try.

    I use the Sinclair tool which measures the distance to the base of the cartridge and the base of the bullet when it is touching the lands from the same reference surface. The difference in those distances is the base to ogive distance of chamber in that particular rifle. I use that distance and an average bullet to set up my seating die.

    Try as I might, the base to ogive distance doesn't come out identical on each loaded round - there are variations of a few thousandts. If I sort the bullets based on base to ogive distance the variation is reduced.

    Unless each individual bullet is adjusted for base to ogive distance, or the seating die touches the bullet ogive exactly at the same location the lands will, there is going to be variation induced by variations in bullet geometry.

    I must be missing something here. What is it?

    Fitch