Dip-Casting Bullet Weight Experiments - Graybeard Outdoors
 
LinkBack Thread Tools
post #1 of 8 (permalink) Old 03-17-2017, 10:18 PM Thread Starter
Member
 
Join Date: Nov 2002
Location: Central Texas
Posts: 456
Default 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, Author of the Browning BPCR book
http://www.texas-mac.com
As Warren Miller once said "Don't take life seriously because you can't come out of it alive."
texasmac is offline  
Sponsored Links
Advertisement
 
post #2 of 8 (permalink) Old 03-17-2017, 10:50 PM
Senior Member
 
Join Date: Jan 2010
Location: South Central Wisconsin, USA
Posts: 10,990
Default

Well done

Anyone who wants to fundamentally change the USA is not a Patriot.
Many things in life are negotiable but not Honor or Integrity.
Celebrating the 2nd Independence Day of the USA as of Noon on Jan.20 2017, We have thrown off the yoke of bondage of the Dem/Socialists and taken back our Constitutional Republic.
gcrank1 is offline  
post #3 of 8 (permalink) Old 03-18-2017, 04:02 AM
Senior Member
 
nanuk-o-dah-nort's Avatar
 
Join Date: Oct 2010
Location: Smack Dab in the middle of God's Country! Saskatchewan, Of Course!
Posts: 1,691
Default

your finding appear to run counter to scientific norms.

one question

my understanding is when tin in alloyed into lead, it becomes homogeneous, therefore cannot separate into layers, as they are alloyed in the molecular level

Could you do one more experiment?

Cast, using the stir technique, X number of bullets from the top of the alloy pot, and X number from the bottom , and test for tin content.

then let your lead pot sit for 8 hours or more, then dip X bullets from the top, and bottom pour X, and test for tin

I'd be interested in the results


this has me scratching my head.... vodka, a similar alloy doesn't have the alcohol separate out of water...

I am ONLY responsible for what I say
I am NOT responsible for what you THINK I said
nanuk-o-dah-nort is online now  
Sponsored Links
Advertisement
 
post #4 of 8 (permalink) Old 03-19-2017, 12:52 AM Thread Starter
Member
 
Join Date: Nov 2002
Location: Central Texas
Posts: 456
Default

Quote:
Originally Posted by nanuk-o-dah-nort View Post
your finding appear to run counter to scientific norms.
one question
my understanding is when tin in alloyed into lead, it becomes homogeneous, therefore cannot separate into layers, as they are alloyed in the molecular level
Could you do one more experiment?
Cast, using the stir technique, X number of bullets from the top of the alloy pot, and X number from the bottom , and test for tin content.
then let your lead pot sit for 8 hours or more, then dip X bullets from the top, and bottom pour X, and test for tin
I'd be interested in the results
this has me scratching my head.... vodka, a similar alloy doesn't have the alcohol separate out of water...
You're not the only one that questioned my conclusion for the same reason. I did some more research and posted the following on several forums.
==================
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. The 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, Iím scratching my head and may have to run some more experiments to figure out whatís happening. There is a possibility that some of the weight changes could be related to a temperature stratification issue, but thereís 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.
==================

I certainly agree that additional experimenting is in order & your suggestions seem like good ones. I will report the results here.
Wayne

NRA Life (Benefactor & President's Council) Member, TSRA Life Member, NSSF Member, Author of the Browning BPCR book
http://www.texas-mac.com
As Warren Miller once said "Don't take life seriously because you can't come out of it alive."
texasmac is offline  
post #5 of 8 (permalink) Old 03-19-2017, 09:10 AM
Senior Member
 
Join Date: Jan 2010
Location: South Central Wisconsin, USA
Posts: 10,990
Default

Or you may have hit upon something? Just because it defies the accepted norm doesnt mean it is wrong; lots of other things in reloading that have gone that way.

Anyone who wants to fundamentally change the USA is not a Patriot.
Many things in life are negotiable but not Honor or Integrity.
Celebrating the 2nd Independence Day of the USA as of Noon on Jan.20 2017, We have thrown off the yoke of bondage of the Dem/Socialists and taken back our Constitutional Republic.
gcrank1 is offline  
post #6 of 8 (permalink) Old 03-24-2017, 06:17 PM Thread Starter
Member
 
Join Date: Nov 2002
Location: Central Texas
Posts: 456
Default

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 take nanuk-o-dah-nort's suggestion & 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. Iím 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.

Thatís it for me. I donít plan on additional experiments on this subject. Iíll 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/magazi...l89partial.pdf

Wayne

NRA Life (Benefactor & President's Council) Member, TSRA Life Member, NSSF Member, Author of the Browning BPCR book
http://www.texas-mac.com
As Warren Miller once said "Don't take life seriously because you can't come out of it alive."
texasmac is offline  
post #7 of 8 (permalink) Old 03-24-2017, 10:11 PM Thread Starter
Member
 
Join Date: Nov 2002
Location: Central Texas
Posts: 456
Default

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

NRA Life (Benefactor & President's Council) Member, TSRA Life Member, NSSF Member, Author of the Browning BPCR book
http://www.texas-mac.com
As Warren Miller once said "Don't take life seriously because you can't come out of it alive."
texasmac is offline  
post #8 of 8 (permalink) Old 03-26-2017, 08:26 PM
Senior Member
 
nanuk-o-dah-nort's Avatar
 
Join Date: Oct 2010
Location: Smack Dab in the middle of God's Country! Saskatchewan, Of Course!
Posts: 1,691
Default

Wow! You did a LOT of work on this.

thanks for the update.

the great thing about the scientific method is we have to be willing to accept we were not exactly correct.

"Stir the Pot"

that is what I do Best!


that remains great advice at any time, any technique.

it will help keep any differentials to a minimum.

I am ONLY responsible for what I say
I am NOT responsible for what you THINK I said
nanuk-o-dah-nort is online now  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Graybeard Outdoors forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome