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Thread: Dip-Casting Bullet Weight Experiments

  1. #1
    Boolit Master
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    Dip-Casting Bullet Weight Experiments

    I just posted an article titled, Dip-Casting Bullet Weight Experiments. For some time I’ve been unsatisfied with the variations in bullets weights when dip-casting bullets for my Browning .40-65 BPCR. So I ran some experiments to identify the root cause, which turned out to be a success. For the details click on the following link: http://www.texas-mac.com/Dip-Casting...periments.html

    Wayne
    NRA Life (Benefactor & President's Council) Member, TSRA Life Member, NSSF member
    http://www.texas-mac.com

  2. #2
    Boolit Master BNE's Avatar
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    Interesting test and a good write up.

    Question: Do you think the lead / tin ratio would change from the top of the pot to the bottom of the pot? (Assuming it was properly mixed, fluxed then allowed to "settle"?
    I'm a Happy Clinger.

  3. #3
    Boolit Buddy
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    Thanks for sharing your knowledge! I found the article enlightening!

    For the record, I'm a new caster. Tonight I managed a weight difference of 1 gr +/-, 500 gr 45-70 bullets (30-1 lead) in a random quality check, about every 20 boolits. (weight average 508 before lubing)
    Mold was a Lyman 457125.

  4. #4
    Boolit Master

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    I have found with these big long bullets the ladle pour and over pour gives me the best results. Getting the lead in hot and at the right flow so the bullet is molten completely Is achieved easier for me. I don't pour a sprue but a ladle full of lead letting the excess run back into the pot. This keeps the bullet, base. and sprue plate hot as long as possible giving good looking sharp bases and sharp corners. Ive been as good as a 1 grn ( +/- .5 grn) variance over a 4 hour session. A little experimenting with your mould and technique helps consistency a lot also.

  5. #5
    Boolit Master
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    I posted the comments and the link to my article on several other BPCR forums & received a couple of responses that has me 2nd guessing my conclusion from the experiments. Both responders indicated that when tin is alloyed with lead, the result is a homogeneous mixture or solution, meaning the tin cannot separate, stratify & form a higher concentration in the upper portion of the pot as I suggested. Since additional research on the subject indicates that to be the case, I’m scratching my head and may have to run some more experiments to figure out what’s happening. There is a possibility that some of the weight changes could be related to a temperature stratification issue, but there’s no question that the percentage of tin in the alloy dropped throughout the casting sessions when the pot was not stirred. Regardless, stirring the alloy still applies.

    Wayne
    NRA Life (Benefactor & President's Council) Member, TSRA Life Member, NSSF member
    http://www.texas-mac.com

  6. #6
    Boolit Master
    Chill Wills's Avatar
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    Hello Wayne, It will be interesting to see what you come up with. Because the various opinions on this, some founded in metallurgy and some in repeated internet wisdom I chose to not respond earlier.
    I think I will just stick my toe in.....
    This subject rhas had my interested for decades because of the conflicting ideas that get floated. I used to have dinner with Bill Ferguson 10 plus years ago when he would attend the AZ longrange matches and his opinions agreed with Art Green, who would talk you ear off when you called and ask questions. I consider them two good sources of info.
    Me, I just restate what I think I know and site the sources......
    I think you are on the right track, you can not separate the tin and lead nor will it settle out but something is causing noise in the data. Additionally, at 800 F, tin and lead oxidize at roughly close to the same rate. In other words, dross of a tin-lead mixture will be close to the same ratio as was the base metal.


    For what it is worth, I have tracked my casting for match bullets, plotted the weight changes as cast and have had much the same experience you have. I have not done anything like the SG testing you have. That was interesting to read.
    Because I can cast well enough, I gave in to just having match quality bullets that I am sure are good enough to win if I do my part.
    I have cast and shot my share of Lead-tin bullets but you may know,( or not) I mostly like Pb-Sn-Sb alloy for my BPCR bullets now.
    Thank you for sharing all the work you put in on this and other areas of casting, loading Black and the Browning rifles. You are always a thoughtful writer and tester and it make for a good read.

    -Michael Rix
    Chill Wills

  7. #7
    Boolit Master dave roelle's Avatar
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    Hi Wayne

    I have years of production diecasting experience with zinc alloys

    And magnesium alloys------both use mechanical mixers in the holding pots to assure uniform alloy composition-------

    Dave

  8. #8
    Boolit Master

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    One thing Ive taken to doing when casting now is when filling the ladle I push it to the bottom of my big pot and make a "swirl" with it to mix and fill the ladle with the hot alloy. This swirl is probably about 6"-8" in dia and seems to keep things more consistant for me. Maybe a low speed mixer with just a flat blade and back and forth motion to constantly agitate the pot

  9. #9
    Boolit Master


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    have you checked for air pockets in the cast bullets?

    what's helped me with that issue is to unload the entire, full ladle into and over the mould - this helps even out the heat and to release any trapped air that's typically present near the sprue hole. that and doing a consistent angled pour into the mould and continue pouring 'til the mould is vertical, then just unload the entire ladle's remaining lead over the sprue hole.

  10. #10
    Boolit Buddy
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    Good read and thanks for sharing.
    I am a dipper since I'm relatively new to casting. I think dipping might stir the pot.

    I am just dropping some casting porn here from over the week-end. 500 gr 30-1 boolits using a lyman 457125 mold.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  11. #11
    Boolit Master
    Chill Wills's Avatar
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    Those look good!
    I was (and still am) a big fan of the design. I used it to move my way from never ever silhouette match shooter to master class. Great bullet!
    Even tho we get wrapped up in good, better, best bullet design, the so called improvements are small and the Lyman 125 remains is as good as it ever was. And that is pretty good!
    Chill Wills

  12. #12
    Boolit Buddy iplaywithnoshoes's Avatar
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    The alloy that is inside the pot is not a SOLUTION, therefore it cannot be perfectly isotropic. Solidified tin and lead alloys are actually a solid MIXTURE and still remain as a mixture when molten. Convection and settling certainly occur in the molten state. I believe that your initial conclusion concerning density might be correct. If this were a Pb-Sn-Sb alloy however, Sn and Sb are right next to each other on the periodic table, so separation only occurs from oxidation out of SOLUTION of Tin and Antimony. These two are still in a MIXTURE with the lead.

    shoe

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
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