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Thread: Making bullet molds

  1. #41
    Boolit Master

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    I gotta agree with all that's been said about working dimensional tolerances and accuracy by you guys. And I totally agree with the concept that using a single cavity mold increases your chances of getting bullets with the minimum weight and size deviation. This seems to me to be a practical concept for rifle shooter seeking the best possible accuracy in a rifle. But its a tradeoff of production rate vs quality.

    I have focused my efforts on producing multi-cavity molds made to achievable dimensional standards that will produce bullets of adequate accuracy for the intended use, intended primarily for handgun level cartridges. (The truth is, I'm trying to make a mold that I would want to buy, own, and use. I'm trying to satisfy ME.)

    I think that if I can control the diameter and depth to -0.000 +.001 from hole to hole that will at least be as good as the mass (not custom) produced molds currently available. And by lathe boring I can compensate for tool wear by just moving the cross-slide out a little more, so as long as the tool wears evenly there shouldn't be any change in profile or overall decrease in hole sizes from start to end of a batch. And my experience has been that (a) a lathe bores a lot rounder hole than any milling machine, and (b) by keeping the blocks together during boring you eliminate a lot of the cutter wobble and cavity edge burring that comes from all sorts of places when using the traditional compound-vise-and-cherry method.

    I'm sure other people have different needs and standards, but I think that a lot of people would be satisfied to have a five or six cavity handgun bullet mold that would drop all the bullets to the proper minimum size +0.001". But I could be wrong.

    (Not a big sports fan, my only fascination with football is that unlike serialized television the outcome isn't really predictable from the start. I seen the same plots rehashed so many times that I can't even get interested in TV anymore unless its the History, Military or similar channel.)

  2. #42
    Boolit Master




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    perfessor
    Now all I have to do is get my lathe, learn how to use it and start making things. You know that you have done it now don't you, no fair laughing
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  3. #43
    Boolit Master

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    Its as addicting (and frustrating and satisfying) as bullet casting and gun collecting and shooting...

  4. #44
    Boolit Master


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    [QUOTE=theperfessor;801281]The truth is, I'm trying to make a mold that I would want to buy, own, and use. I'm trying to satisfy ME.

    Not a big sports fan, my only fascination with football is that unlike serialized television the outcome isn't really predictable from the start. I seen the same plots rehashed so many times that I can't even get interested in TV anymore unless its the History, Military or similar channel.

    I see that we agree on a lot of things!

  5. #45
    Boolit Master

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    Quote Originally Posted by deltaenterprizes View Post
    Willbird,
    I have read about Schutezen rifle shooters that use single cavity nose pour molds for that same reason.

    .
    Some of them even went so far as to shoot the bullets in the order they were cast too.
    Both ends WHAT a player

  6. #46
    Boolit Master

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    I read in a book called "The Arms of Krupp" (?) that the German engineers calculated the increase in bore size due to thermal expansion and erosion and numbered the rounds used in Big Bertha. You didn't dare shoot them out of order or at the wrong pace of fire! IIRC the barrels were shot out after just a couple of hundred rounds.

  7. #47
    Boolit Buddy machinisttx's Avatar
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    Quote Originally Posted by theperfessor View Post
    I'm sure other people have different needs and standards, but I think that a lot of people would be satisfied to have a five or six cavity handgun bullet mold that would drop all the bullets to the proper minimum size +0.001". But I could be wrong.
    I agree with this.



    And thanks for the info on the carbide.
    Machinists do it with precision.

  8. #48
    Boolit Bub Chuck_ls's Avatar
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    Great article, Prefessor. I have made both lathe bored and cherry cut molds in the past with satisfactory results. I like your male/female pins for aluminum blocks. I will have to try that if I try again. Thanks for sharing.
    Chuck

  9. #49
    Boolit Master


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    Saints won! Lol!!!!!!!!!!

  10. #50
    Boolit Master

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    Deltae-

    Yeah they did. They played a little better game and took a chance that worked out for them. Can't begrudge them for that. Now you know why I don't bet on sports!

    Just to check my assumptions of tolerances for multi-cavity molds for handgun bullets, I did a few calculations. These calculations are based on the density of pure lead and assumes the bullet is a true cylinder of the length and diameter listed in the table. The length was selected to yield a popular bullet weight for the two calibers listed (.38 and .44).

    I note that a 0.001" change in length causes less percent change in weight than a 0.001" change in diameter under these assumptions. which makes sense when you think about it. It also indicates to me that diameter is the more sensitive value and maintaining diameter to as close a tolerance as possible is the key to consistent bullets.

    (P.S. I got your email w/photos, I'll post them in a new thread when I get unburied here in a few days.)
    Attached Thumbnails Attached Thumbnails size_vs_weight.bmp  

  11. #51
    Boolit Master

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    Chuck_Is -

    Noticed this was your first post. Welcome to the insanity! It really is a great place to learn and share with other like-minded folks. Appreciate your kind words. I'll be glad to send you CAD file of pins if you want it. I've worked through several designs and have what I think is a good pin design that is both accurate in alignment and easy to manufacture. It is different than that shown in original story. I also have determined proper fit up to prevent pins from loosening due to thermal expansion differences between steel and aluminum.

    Post some of your stuff. preferably with photos. The folks here LOVE photos and it helps explain narrative.

  12. #52
    Boolit Master
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    Any updates on the molds.
    Updates on process improvements?
    Is Professor still on the forum?

  13. #53
    Boolit Master




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    We lost the Professor earlier this year.
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  14. #54
    Boolit Master
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    theperfessor is alive and well and posting actively on another forum. His username there is KeithB

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  15. #55
    Boolit Master




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    Brain fart it was Recluse we lost not the Professor
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