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#11906412 - 03/17/17 Dip-Casting Bullet Weight Experiments  
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texasmac Offline
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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_Bullet_Weight_Experiments.html

Wayne

Last edited by texasmac; 03/17/17.

NRA & TSRA Lifetime member. NSSF member. Author & Publisher of the Browning 1885 BPCR book.
See www.texas-mac.com
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#11908903 - 03/18/17 Re: Dip-Casting Bullet Weight Experiments [Re: texasmac]  
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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 & TSRA Lifetime member. NSSF member. Author & Publisher of the Browning 1885 BPCR book.
See www.texas-mac.com
#11915901 - 03/21/17 Re: Dip-Casting Bullet Weight Experiments [Re: texasmac]  
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Could your alloy be too hot, burning off the tin as you cast?

Ed


"Not in an open forum, where truth has less value than opinions, where all opinions are equally welcome regardless of their origins, rationale, inanity, or truth, where opinions are neither of equal value nor decisive." Ken Howell

#11919400 - 03/22/17 Re: Dip-Casting Bullet Weight Experiments [Re: texasmac]  
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I used to work in a solder factory. We made the entire gamut of products from solder up through welding wire.

1) We used tin in with copper. Copper melts at a much higher temp. I never heard of tin burning off. The components included tin, antimony, copper and silver.

2) We used magnetic flux to stir our alloy as it was melting. However, the actual casting was done in a bottom-pour arrangement in a separate vessel with no stirring. A pour might last an hour.

3) The only time I heard of alloy being lost to the air was when we had an accident on the platform and an entire batch washed out. We estimated that 800 lbs of alloy vaporized instantaneously and got carried out through the ventilation. No deaths. 1 injury-- a guy lept from the platform to save himself from being scalded to death and missed the railing on the other side of the pit.


A lot of folks collect sprue and such and wait until the end of the pouring session to remelt it. One thing I do, is keep my temps up a bit and pour the sprue and scrap back in to my melter periodically. It makes for a more homogenous pour. I'll pour maybe 10 castings, knocking the sprue into a separate metal pot, and then throw the contents of the sprue pot back into the melter and keep going.



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#11920347 - 03/23/17 Re: Dip-Casting Bullet Weight Experiments [Re: APDDSN0864]  
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texasmac Offline
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Originally Posted by APDDSN0864
Could your alloy be too hot, burning off the tin as you cast?
Ed


Ed,

I assume you meant to say boiling off the tin. Although pure tin melts at about 450 degrees F, the boiling temp is 4,716 degrees F, so there's no possibility it boils off.

Wayne


NRA & TSRA Lifetime member. NSSF member. Author & Publisher of the Browning 1885 BPCR book.
See www.texas-mac.com
#11923315 - 03/24/17 Re: Dip-Casting Bullet Weight Experiments [Re: texasmac]  
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Due to the previous results of my bullet weight experiments, which conflicted with normally accepted understandings of a homogeneous lead/tin alloy mixture, I decided to run some additional tests.

1st session:
To check the homogeneous nature of the alloy, the pot was filled with 20:1 alloy, fluxed & allowed to set for 7 hrs. Using the bottom pour feature, several bullets were cast & the lead/tin ratio measured. Then, by gently filling the ladle from the top of the alloy to minimize disturbing the alloy, several bullets were cast & the lead/tin ratio measured. The ratio of the alloy from the top of the pot was 18.5:1 and 19.5:1 from the bottom.

2nd session:
The above test was repeated after allowing the pot to set for an additional 8 hrs. The ratio of the alloy from the top & bottom of the pot was 19.5 & 19.7 respectively.

3rd session:
Finally, the test was repeated after letting the pot set overnight (approximately 12 hrs). The resulting alloy ratio from the top & bottom of the pot was 18.8 & 17.0 respectively.

The above results tend to support a homogeneous alloy versus what I measured in the earlier experiments for which I have no explanation. I’m beginning to wonder if unseen voids in the bullets affect the specific gravity (alloy ratio) measurements.

But I needed to cast up a batch of bullet for an upcoming match. So 60 bullets were cast while stirring the alloy. The result was a total weight spread of 0.8grs and the average lead/tin ratio measured at the start and finish was 20.2:1 +/- 0.2, which essentially confirmed my results from previous sessions when stirring the alloy while casting.

That’s it for me. I don’t plan on additional experiments on this subject. I’ll just be sure to stir the pot during future casting sessions. By the way, a forum member reading the results of my experiments referred me to an excellent article that was published in the Jan./Feb. 1981 issue of the Hanloader magazine. Titled, Weight Variations in Cast Bullets, it can be accessed at https://www.riflemagazine.com/magazine/PDF/hl89partial.pdf

Wayne


NRA & TSRA Lifetime member. NSSF member. Author & Publisher of the Browning 1885 BPCR book.
See www.texas-mac.com
#11924048 - 03/24/17 Re: Dip-Casting Bullet Weight Experiments [Re: texasmac]  
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texasmac Offline
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Ok guys,

The light finally came on & I believe I’ve figured it out. After a little more research and another small experiment, it became clear that unseen voids in bullets have a direct affect on measurements of specific gravity (SG). Archimedes’ principal, which is the bases for SG measurements, states that “Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object”. Therefore, since a bullet will displace the same volume of water regardless of the size of internal voids, SG measurements are inversely proportional to the size of the void. I.e. when using the air versus water weight technique to measure SG, the SG of a bullet with a large void will be lower than the SG of an identical bullet with a small void. Hence, the large-void bullet measurement will imply a smaller lead/tin ratio. E.g. using a 530gr bullet cast with 20:1 alloy, if another bullet from the same batch weighs 529gr due to a 1.0gr void, the SG of the 529gr bullet will incorrectly suggest the alloy ratio is 18.6:1. Therefore, when measuring SG to determine the lead/tin ratio of an alloy, it’s wise to use bullets that fall within the upper end of the weight spread, indicating minimum voids.

So, given the above, I reviewed my data from the original experiments that incorrectly suggested the lead/tin ratio of the alloy was increasing as bullets were being cast. I found that when starting the casting sessions all initial measurements of the SG were based on bullets that were slightly lighter weight than those cast later in the session. So it’s a good bet the initial bullets had slightly larger voids, which diminished as the mould temperature increased. Although I was using a hot plate to keep the mould hot between sessions, apparently it was not hot enough.

As to why the weight spread diminished from session to session, I have no clue. It may be the result of subconsciously improving my casting and/or measuring techniques.

BTW, I now know the original experiments and my assumption were incorrect. And I’m convinced that lead/tin alloys are a homogeneous solution. The tin will not stratify in the alloy solution and neither will the lead/tin ratio change due to fluxing or removing the dross. Therefore I plan to remove the original article from my website.

Wayne

Last edited by texasmac; 03/24/17.

NRA & TSRA Lifetime member. NSSF member. Author & Publisher of the Browning 1885 BPCR book.
See www.texas-mac.com
#11924292 - 03/24/17 Re: Dip-Casting Bullet Weight Experiments [Re: texasmac]  
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Wayne,...it's easily TEN years since SSE published my article on "Maintaining Co-efficients of thermal equilibrium" and IIRC you were really critical of the LARGE capacity ladle (s?) I sent over to you to try,...."too heavy, awkward, ...etc."
Quote
As to why the weight spread diminished from session to session, I have no clue. It may be the result of subconsciously improving my casting and/or measuring techniques.

Looks like maybe you're STARTING to catch on,...and I'm thinking that if you were to make ONE simple change,....e.g. a LARGER, heavier Ladle for LARGER, heavier bullets, you might just finally get it.
That little one pictured just doesn't hold enough alloy to do anything BUT give you the results you're getting,it's damned near EMPTY by the time the mold's full.

If it wasn't you I sent the free sample ladle over to, I wish it had been,....let me know, and I'll send one NOW,....and would be interested in seeing your casting bell curve after making ONLY that change in your process.

Cheers,

GTC




Last edited by crossfireoops; 03/24/17.

Member, Clan of the Border Rats
-- “Sometimes I wonder whether the world is being run by smart people who are putting us on or by imbeciles who really mean it.”- Mark Twain





#12043883 - 05/20/17 Re: Dip-Casting Bullet Weight Experiments [Re: crossfireoops]  
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Mac, thanks for the info/correction on the boiling point of tin.

Originally Posted by crossfireoops
....e.g. a LARGER, heavier Ladle for LARGER, heavier bullets...That little one pictured just doesn't hold enough alloy to do anything BUT give you the results you're getting,it's damned near EMPTY by the time the mold's full.
Cheers,
GTC


Being the proud owner of both a Cameron Dumpster Ladle and a Cameron Double Dumpster Ladle (for two cavity molds) I can attest to the consistency of bullet weight and mold fill-out when pouring into large caliber molds. They provide sufficient pressure and alloy temperature (due to higher thermal mass) to fully fill out the large cavities.

Ed


"Not in an open forum, where truth has less value than opinions, where all opinions are equally welcome regardless of their origins, rationale, inanity, or truth, where opinions are neither of equal value nor decisive." Ken Howell

#12044007 - 05/20/17 Re: Dip-Casting Bullet Weight Experiments [Re: texasmac]  
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Never occurred to me that stratification due to temp would be an issue, nor that tin would be influenced is such fashion. Am of the opinion however that it can and does oxidize more quickly that other alloy constituents and thus we flux it. Repeatedly.


I am..........disturbed.

I always wondered what the job application is like at Hooters. Do they just give you a bra and say, “Here, fill this out?”



#12044026 - 05/20/17 Re: Dip-Casting Bullet Weight Experiments [Re: texasmac]  
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crossfireoops Offline
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If you can see clean shiny melt at the top of a 25 lb Castmaster, at just about ANY time during the complete consumption of the contents of your days, or casting session's run,,,,,,you're not doing it right, and you WILL loose your ratio balance in the process.

You can ADD flux, during your casting session,......WITHOUT disturbing the existing, nasty looking mess on top of your pot,......

alla' this while maintaining what I started calling a "Coefficient of thermal equilibrium",......moons ago.

GTC


Member, Clan of the Border Rats
-- “Sometimes I wonder whether the world is being run by smart people who are putting us on or by imbeciles who really mean it.”- Mark Twain





#12046358 - 05/21/17 Re: Dip-Casting Bullet Weight Experiments [Re: texasmac]  
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DigitalDan Offline
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Is that your way of saying flux in one hand and...? laugh


I am..........disturbed.

I always wondered what the job application is like at Hooters. Do they just give you a bra and say, “Here, fill this out?”



#12046519 - 05/21/17 Re: Dip-Casting Bullet Weight Experiments [Re: texasmac]  
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Nope,.....well timed fluxing the melt from the bottom up is the stuff of very narrow bell curves, when you weigh your "run".

Take careful, VERY careful note that I've not said a thing about stirring it in from the top,......that being something that i may do once, in the process of running off well over 20 lb of good BPCR alloy,.......and in deference to breaking the very fast pace of moving .800 lb of melt per double pour, into 550 gr cavities.........and again,.....within that "equilibrium" discussed above,..... one eye on the the immersion analogue thermometer the Old Antimony Man gifted me moons ago,..... one eye on the slag build up on the very large square area comprised by the size of the ladles discussed, and every now and than QUICKLY sprinkling a little pre dried / heated "LETS" flux, raw beeswax, or sawdust, or quality pitch into the big ladle and through inverting it on it's way down to the bottom,....and then slowly turning it back up into the normal "Fill position", strir and scrape like crazy,.....thereby cleaning (first, foremost, and MOST importantly) the INSIDE of the ladle,.....also bringing up all sortsa' yellow tinged gack to the top,.....where it can bloody well stay in all of it's disgusting, and crusty glory, ....for the FRA I give about that.

Remember, I'm using a BIG bottom pour ladle,.......not some stupid little "cherry" sized toy that can barely produce 180 grain slugs by virtue of built in , and FUNDAMENTAL design problems,.......the damned things were OK for round balls,.....and that's about it.

EWIW, I think that the stuff sold under the handle "Marvelux" is garbage, and one of the more insidious and unidentified sources of rust and corrosion available to the unwitting "consumer" today,.... I won't have that nasty chit on my property,.....much less inside of one of my buildings, ....it's worse in terms of being hygroscopic than a lot of the very hot fluxes I use for a variety of Silver Solders. I think the people vending it are allowed to sweep up under the production lines producing those ,....on the weekend.

Look,...."Too many Letters" has been through this curriculum, and can vouch for how FAST, hassle free, and damned effective method is,.....he's seen it work, and I'd venture is now doing better work than I. Get somebody out here with a decent video camera, and we'll put it on a disc / DVD,.....I'm great with a MARGINAL profit for so doing,.....

We're not flying these big slugs to Mars, they're NOT complicated or challenging....and NONE of this has to go into the realm of rocket science to generate a good, desirable end product.

A LITTLE understanding of physics, and the properties of metals in a fluid state will suffice.

and I can tell ya' this,....there appear to be some who'll bullheadedly REFUSE to get it right, and continue to fail in their efforts.

GTC


Member, Clan of the Border Rats
-- “Sometimes I wonder whether the world is being run by smart people who are putting us on or by imbeciles who really mean it.”- Mark Twain





#12046552 - 05/21/17 Re: Dip-Casting Bullet Weight Experiments [Re: crossfireoops]  
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Originally Posted by crossfireoops
...."Too many Letters" has been through this curriculum, and can vouch for how FAST, hassle free, and damned effective method is,.....he's seen it work, and I'd venture is now doing better work than I.
GTC


With your tutorial, the ladles you built for me, and a follow-up session with "Paladin" at my place a few years back, I learned enough to have "sharpsguy" look at the slugs I poured for my Shiloh and comment that there didn't appear to be anything else he could teach me about casting bullets.

Coming from him, that's high praise, indeed!

The investment in the "Dumpster" ladles was well worth every penny.

Ed

Last edited by APDDSN0864; 05/21/17. Reason: kaint spel ner typ

"Not in an open forum, where truth has less value than opinions, where all opinions are equally welcome regardless of their origins, rationale, inanity, or truth, where opinions are neither of equal value nor decisive." Ken Howell

#12047674 - 05/22/17 Re: Dip-Casting Bullet Weight Experiments [Re: texasmac]  
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A ladle plenty big enough to hold at least twice as much melt as needed for the bullet is good. The new Lyman ones hold way more than enough but the dang handles are to long so it's necessary to shorten them. I run the temp in the pot at 775 for bpcr bullets. I also cast with two moulds , that seems to help keep things very even. If casting with a single mould block then the locking mould handles make for extreme consistency in bullet weight.


the most expensive bullet there is isn't worth a plug nickel if it don't go where its supposed to.
www.historicshooting.com
#12047715 - 05/22/17 Re: Dip-Casting Bullet Weight Experiments [Re: texasmac]  
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One other thing that might be of assistance in casting consistent bullets. It's not a project for a rainy day, seems the high humidity levels will raise holyned with consistency. I asked a commercial bullet caster I know about that, and he said yes, that and a drastic change in barometric pressure could deal him fits even with the high dollar casting machines


the most expensive bullet there is isn't worth a plug nickel if it don't go where its supposed to.
www.historicshooting.com

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