Is it possible that the ogive could vary .030" on different lots of Bergers?

Discussion in 'Reloading' started by Troutslayer2, Oct 14, 2010.

  1. Troutslayer2

    Troutslayer2 Well-Known Member

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    I am working with a bunch of data and unfortunately I don't have any bullets from my last lot, just some new ones. Is this possible that there could be a .03" variance in the placement of the ogive from one lot to the next? It kind of seems like a large margin. If I were to just load them without making this check, I would be jamming a round that used to jump. Is this likely, or do you think my measurements are off?
     
  2. winmagman

    winmagman Well-Known Member

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    I've seen bullet length (base to ogive) vary from lot to lot, never .030 but that doesn't mean it can't happen.

    As far as going from jumping to jammed, it shouldn't happen. The seating die contacts the ogive(should anyway) to seat the bullet at a length detemined from the shell holder to the seating stem on the ogive. If the new bullets are .030 longer(base to ogive) all that will change is that there will be .030 more bullet inside the case. This of coarse can change pressure and may require tweaking of a known load.

    Chris
     
  3. Troutslayer2

    Troutslayer2 Well-Known Member

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    Thanks for that. My confusion in it is that if I make my OAL the same from one lot to the next, my ogive is not necessarily in the same place because of the variation. I guess I need to start basing all of my work off the ogive instead of the OAL.
     
  4. winmagman

    winmagman Well-Known Member

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    My mistake, I assumed you were working off the ogive for everything, I should have asked.

    You are partially correct though, if you measure to the bullet tip your measurements can be all over the place, even within the same lot of bullets. However, the seating die will still put the ogive at the same place as the previous lot if you haven't changed its setting.

    Chris
     
  5. phorwath

    phorwath Well-Known Member

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    I thought the definition of ogive was where the bullet changed from straight bore diameter to beginning the taper towards the meplat. Ogive is where the bullet would first contact the rifling if a bullet was inserted tip first into the bore.

    None of my seating die stems make contact with the bullets at this location (ogive). They all contact the bullet midway between the meplat and ogive. So if the location of the ogive was varying by 0.030", it could be possible for some bullets to be contacting the rifling while others would not.

    I measure seating depth from case head to ogive using a device manufactured and sold by Hornady - "Lock n Load" something or another. Not at my reloading bench right now or I would have taken a look.

    I guess I am disagreeing with you Chris, based on the locations where all of my bullet seating die stems contact the bullets. What kind of bullet seating dies are you using that contact at the ogive?
     
  6. winmagman

    winmagman Well-Known Member

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    Well.....I just had an "I'll be damned" moment.

    Your post sent me off to the reloading bench to do some die measuring, something I haven't done before.

    I assumed the seating die would be just under the diameter of the bullet i.e. .240 or so for a .243 (the die I measured) turns out that is not the case. It actually measures .230, which also happens to be the size of the hole in tha Stoney Point comparator insert that I have. Just lucky I guess.

    However, I can now see how there could be the possibility that circumstances could allow for going from jumping to jammed.

    I guess I just learned something new. Appreciate the lesson.


    Troutslayer2,

    Sorry for the misinformation, next time I'll know better.

    Chris
     
    Last edited: Oct 14, 2010
  7. Mikecr

    Mikecr Well-Known Member

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    You guys got a few things confused.
    The ogive is not a datum or specific point of a bullet nose. It is the entire curved portion of a nose, and only expressing the radius of it. The radius of a circle is not defined by a specific point on a circumference.
    And the reason seater stems contact where they do has nothing to do with your barrel/throat. Contact too low can distort the nose, and contact too high produces inconsisteant seating (that varies with seating force).

    There is no standard datum for bullet noses, and all our tools and seater stems take a set at different points on our bullet noses. Doesn't matter.
    All that's important is that you stick to the same tool, with it's consistent datum(hopefully), that you determined the best seating depth with.

    Trout, bullets do vary from lot to lot. They are not made to a blueprint. But have you used the exact same tool for your measurements?
     
  8. phorwath

    phorwath Well-Known Member

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    Mikecr,

    Thanks for jumping in as I'm up to learning proper terminology. Is there a definition for the location on the bullet where the bullet first contacts the rifling?

    Do you agree that the only way to know how far the bullet is seated away from the lands is to take the measurement from the case head to the bore diameter on the bullet? Which I might have wrongly defined as the 'ogive' (where the bullet first contacts the lands) in my initial post? Because I commonly measure differing OAL from case head to the tip of the seated bullets when I have closely controlled the seating depths based on case head to full bore diameter location on the bullet (where the bullet first contacts the lands) using the Hornady tool (which I think Hornady purchased from Stoney Point about one year ago).
     
  9. winmagman

    winmagman Well-Known Member

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    Now I got a question cuz I'm confused. I'll use a 243 bullet for an example.

    Say a bullet is 1" long base to tip.
    Lets say the ogive starts .550 from the base at a diameter of .243.
    Lets say the die contacts at .675 from the base at a diameter of .230.

    Now if the next bullet actually measures 1.005" base to tip, not an unrealistic variation even within the same lot.
    The ogive starts in the same place, same diameter.

    I'm thinking the spot that the die contacts at .230 will no longer be .675 which means the spot that the bearing surface starts will not be the same distance from the lands from bullet to bullet even when measuring from the ogive. If thats the case how the heck do we ever get consistent seating depths with regards to getting the begining of the bearing surface the same distance from the lands every time??

    Is that correct or am I over thinking this?? Or are we talking such small amounts it doesn't matter?

    Thanks for the help.

    Chris
     
  10. winmagman

    winmagman Well-Known Member

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    Phorwath,

    What are you using to measure the bullet at full bore diameter?

    I thought thats what I was doing with my Stoney Point comparator, apparently I was mistaken as all the inserts I have run .010 to .015 under the actuall caliber size they are used for.

    If there is something better out ther I'd like to know.

    Chris
     
  11. Gene

    Gene Well-Known Member

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    Mike is correct. You may yet be a bit confused. First, never measure base of case to tip of the seated bullet. Forget the loading manuals "suggested OAL" cause that's how they do it. You need to find where the ogive touches the lands lightly. There are several ways to do this. I size a dummy round, seat the bullet where I think it will be close, measure it with my Davidson base and nosepiece, write that down. Each time I do this, I first wipe the bullet with 0000 steel wool. Assuming the first attempt was too long, adjust the seater die down about .010" and try again. Do this until the land marks disappear. Pull the bullet up slightly, raise the die adjustment about .005". Eventually, you will very barely see (I use a 6x jewelers loupe to see them) several rub marks where the ogive contacts the lands (you might see just two or three, that is OK). Write that measurement down and keep it for future reference.

    When changing bullet lots, whether Berger or any others, always re-establish the same measurement. Yeah, its a PIA, but you can do it right or not. BTW, I shoot about 2000 Bergers and many others every year, and most of the time, the measurement has to be repeated every time I get a new lot. When you find the lot you like, buy several thou and check the measurement frequently. It will change as the throat wear advances.
     
  12. phorwath

    phorwath Well-Known Member

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    Chris,

    I'll check what Hornady calls their tool on the Hornady packaging, and then add to this post when I get home this evening. I'll also take some inside diameter measurements on my bushings also, and see how they compare to bore diameter. They should be smaller than bore diameter, because rifling to rifling diameter is smaller than groove to groove diameter.

    For example, on a .308 Winchester or 300 Win Mag barrel, the bore dimension from groove to groove will be very close to 0.308". I believe the land to land measurement across the bore will be very close to 0.300 inches on most rifled barrels.

    0.300" is the size bushing that Redding sends out with their comparator tool for .308 caliber rifles. I expect my Hornady tool bushing for .308 caliber bullets will also be very close to 0.300 inches inside diameter, so as to contact the .308 bullets at the location where the bullet will first contact the bore cross-section at the end of the chamber throat. Which would be the rifling land to rifling land diameter.
     
  13. woods

    woods Well-Known Member

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    Typically the comparator insert holes are .011" below caliber. I just measured the comparators I have and got these results

    caliber / comparator hole size

    .264" / .253" (both my comparators measured .253" but on one of them the hole narrowed to .252" further in)
    .284" / .273"
    .308" / .297"
    .338" / .327"
    .375" / .364"

    as measured with pin gauges
    [​IMG]

    why they didn't make the holes .008" so they would hit on the same point on the bullet ogive as the lands do, I don't have a clue!

    Now the seating stems have much smaller diameters where they will first hit the bullet as evidenced by this 30 caliber seating stem from an RCBS standard seating die (the only one I will take apart and measure since I refuse to take my Competition Seaters apart, they are working too well)
    [​IMG]

    Bullets vary greatly, case in point these 2 Accubonds from the same box
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]

    But I've always heard Bergers were amazingly consistant. Maybe not.
     
    Last edited: Oct 14, 2010
  14. phorwath

    phorwath Well-Known Member

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    Thanks woods. The pictures help tell the story.

    I've measured two different boxes of Berger bullets in the past. 100 - 210 grain VLD Hunting .308 bullets. And 100 - 168 grain VLD Hunting .284 bullets. None of the base of bullet to beginning of ogive measurements varied more than 0.003" in either box, and only two or three bullets from each box varied as much as 0.003". The rest were all within 0.002".

    I believe I read where Berger replaced some of their bullet forming dies in some of their calibers recently (within the past 8 months) because the dies were beginning to wear out to the point that bullet to bullet dimensional consistency was not up to 'their standards'. If a person had a box of bullets from a Lot# manufactured before they switched over to their new dies, and a box of bullets with a Lot# from after the dies were replaced, I wouldn't be surprised to see differing measurements. But I would expect bullets within any given Lot# from Berger to be very uniform. Much more so than Nosler Ballistic Tips or Accubonds, which vary much more than Berger's, dimensionally, in my own measurements.