20:1 needed or just BHN 10 for BPCR

[40-82 hiker]

I am needing some help on my alloying of lead and tin. I shoot 45-70 Trapdoor, 40-82 Win. '86, and .40-65 RB (BPCR rifle).

Tin is expensive, so is it a need for accuracy, etc., to use a real 20:1 alloy, or is it just a need for BHN 10, however you get there (COWWs plus pure lead, for example)? I am new to the "molding my own" community (I've been buying my bullets until now), and am trying to get a system going. I have accumulated a considerable stash of COWWs, and some pure lead. I have been trading the COWWs for pure lead, so I can get enough of that metal to keep me in bullets for these rifles. I use the COWWs as such for .45ACP, so with but a little additional tin (1 - 2%) I'll be okay for that.

Please let me know what you are doing as far as alloys are concerned, and sources of tin available. I live in a rather rural area, and there are NO real sources for reclaimed solder. I've tried...

Thanks.

[montana_charlie]

Tin is expensive, so is it a need for accuracy, etc., to use a real 20:1 alloy, or is it just a need for BHN 10, however you get there?
I am somewhat inclined to be a 'purist' on certain things, so I prefer the 'traditional' mix of only lead and tin.
But, truthfully, I don't think there is any real harm in having antimony in the alloy.

A well-known shooter and researcher has recently removed all of his writings fron 'the forums', so I won't mention his name. But I believe he is more knowledgeable than most on the subject of BPCR alloys.
If you believe what his testing proved, that "20-1" you speak of actually has a hardness of 7.8 BHN ... not 10.
However, if you use a non-Lee tester, you must mix your metals to get it to read 10, because that's the way it's calibrated.

Anyway, his favorite metal for "hard" BPCR bullets is called his 'three - seven alloy'.
It is 3 parts Lyman #2 and 7 parts pure lead.
Makeup is 97/1.5/1.5 and is 8.2 BHN when cast. After 18 hours, it stabilizes at 9.8 BHN.

If you really think you need 10 BHN, this will get you close enough.
Now, you just need to check the LASC site to find a mix to simulate Lyman #2 using wheelweights.

CM

[40-82 hiker]

I am somewhat inclined to be a 'purist' on certain things, so I prefer the 'traditional' mix of only lead and tin.
But, truthfully, I don't think there is any real harm in having antimony in the alloy.

A well-known shooter and researcher has recently removed all of his writings fron 'the forums', so I won't mention his name. But I believe he is more knowledgeable than most on the subject of BPCR alloys.
If you believe what his testing proved, that "20-1" you speak of actually has a hardness of 7.8 BHN ... not 10.
However, if you use a non-Lee tester, you must mix your metals to get it to read 10, because that's the way it's calibrated.

Anyway, his favorite metal for "hard" BPCR bullets is called his 'three - seven alloy'.
It is 3 parts Lyman #2 and 7 parts pure lead.
Makeup is 97/1.5/1.5 and is 8.2 BHN when cast. After 18 hours, it stabilizes at 9.8 BHN.

If you really think you need 10 BHN, this will get you close enough.
Now, you just need to check the LASC site to find a mix to simulate Lyman #2 using wheelweights.

CM

Thanks for the info! Actually what started this whole mess for me was the fact that my first batch of 20:1 measured 7.8 (+/-) on a Lee tester. It seemed like I was looking at having to add more tin, which had me worried due to cost and whether or not what I had with tin in it was a known alloy. So, your post gives me confidence that I actually do have 20:1, as you stated the other gentlemen discovered with his research. Do you know if his "hard" BPCR alloy was a reaction to the 20:1 being too soft? Or...

I can always go harder if need be. I might still try a mix of COWWs and pure lead to get BHN 10, as this might be a good exercise. The problem as I see it is that when first starting out it is good to stick with something known, then experiment.

Thank you again.
Bob

[montana_charlie]

Thanks for the info! Actually what started this whole mess for me was the fact that my first batch of 20:1 measured 7.8 (+/-) on a Lee tester.
That happened to me, too, when I first got my tester.
After checking everything three times ... mixing fresh alloy three times ... I piled into the guy who sold me the tin. He got so worked up he decided he must have sent me some 60/40 solder by mistake.

When another run came out 'wrong' with tin from a different source, I apologized to the tin guy and made things straight with him ... then demanded that Lee trade testers with me and send me an accurate one.

When that tester gave the same results, I gave up and started doing whatever it took to make alloy come out at "10 BHN".
I still have a few pounds of that junk. I no longer have any idea what is in it, but it may some ground glass, granite and cast iron in there someplace.

Finally, I just stopped testing lead. I mixed a pound of tin with 20 pounds of lead, and shot whatever came out of the ladle. That worked okay until I wanted to paper patch some Money bullets ...



Do you know if his "hard" BPCR alloy was a reaction to the 20:1 being too soft? Or...

20-1 is soft enough to allow 'nose slump' on certain slim-nosed bullet designs ... such as the Money bullet.
The 'traditional' alloy for something like that would be 16-1 (8.2 BHN) but he wanted to experiment with antimonal alloys as well as lead/tin mixes.

His research was actually meant to discover how alloy hardness changed after casting ... and over extended periods of time.
He checked his test materials for two years, if I remember correctly.

He really liked the 3-7 Alloy for it's long-term stability once it reached it's 'native' hardness.

It was during that test that he learned the actual BHN hardness of traditional lead/tin BCPR alloys are much different than the numbers found in the 'standard charts' which have been in use for decades.
When he posted about those values that he was getting, it renewed my faith in the Lee tester. Suddenly, I could start believing in what it had always been telling me.

If you are getting 7.8 BHN from carefully mixed 20-1 alloy, that just proves you are using good technique with your Lee tester ... which uses the Brinell method to measure hardness, and produces results in actual BHN values.

Press on ...

CM

[ColColt]

20-1 is soft enough to allow 'nose slump' on certain slim-nosed bullet designs ... such as the Money bullet.
The 'traditional' alloy for something like that would be 16-1 (8.2 BHN) but he wanted to experiment with antimonal alloys as well as lead/tin mixes.


I'm glad I saw this. I was getting ready to order either several pounds of tin or a 1:20 alloy from RotoMetals. So, with a bullet like the 535 gr Postell, what's the best alloy...1:20, 1:30 or something a tad harder like 1:16? I have WW's and some Isotope lead left which is around BHN10.

[MT Chambers]

For hunting with cast bullets and BP, I prefer pure lead or very close to it!

[40-82 hiker]

That happened to me, too, when I first got my tester.
After checking everything three times ... mixing fresh alloy three times ... I piled into the guy who sold me the tin. He got so worked up he decided he must have sent me some 60/40 solder by mistake.

It was during that test that he learned the actual BHN hardness of traditional lead/tin BCPR alloys are much different than the numbers found in the 'standard charts' which have been in use for decades.
When he posted about those values that he was getting, it renewed my faith in the Lee tester. Suddenly, I could start believing in what it had always been telling me.

If you are getting 7.8 BHN from carefully mixed 20-1 alloy, that just proves you are using good technique with your Lee tester ... which uses the Brinell method to measure hardness, and produces results in actual BHN values.

Press on ...

CM

This post has saved me more time and trouble than I can imagine. I very much thank you. I would have been terrible for me to have made an alloy such as yourself with granite, ground glass, and cast iron just to find out the same thing you did: all of the charts are wrong! Geez...

I also want to bring up an oddity about the "charts", even the one that came with my casting pot: many charts say that 20:1 alloy is made with 95% lead and 5% tin. This is 19:1. As you so apply stated, 20:1 would be 20 pounds of lead and 1 pound of tin, or 100 pounds of lead and 5 pounds of tin. Again, which is right for the "historical" alloy of 20:1. It cannot be both, so which did the ordnance department come up with in the 1870s or so: 95% and 5% (19:1 actually), or 20:1. Not much of a difference at all, so my argument does not stand on that problem. It is just more of a curiosity, since you brought up the point about the charts concerning the BHN of 20:1 alloy.

Thanks again for your help. Hope you find something to do with that leftover gorilla lead.

[40-82 hiker]

If you are getting 7.8 BHN from carefully mixed 20-1 alloy, that just proves you are using good technique with your Lee tester ... which uses the Brinell method to measure hardness, and produces results in actual BHN values.

Press on ...

CM

I'll pass along your kudos to a friend who did the measurements for me. I do not have the money to purchase a Lee tester at this time, and probably would not try due to the nature of the "industry". Just too painful to wait for back orders...

[montana_charlie]

I'm glad I saw this. I was getting ready to order either several pounds of tin or a 1:20 alloy from RotoMetals. So, with a bullet like the 535 gr Postell, what's the best alloy...1:20, 1:30 or something a tad harder like 1:16? I have WW's and some Isotope lead left which is around BHN10.
You can use 16-1 and it will perform as well for you as it did for the hunters in the 1870s. That is the alloy used to make the bullets the Sharps Company sold.
But, for the 'old standbys of today' ... Postell, PJ Creedmoor, Government, even the PGT bullet ... the soft alloys will do a fine job. Some even use 40-1.

The Money is a relatively new contender, and it's nose is slim enough to need the extra 'spine'.

CM

[ColColt]

The "New Postel" that Steve Brooks makes has a slimmer nose than the old Postel. Would that be considered a problem with possible nose slump as mentioned?

http://brooksmoulds.com/bullets.php

[40-82 hiker]

If you are getting 7.8 BHN from carefully mixed 20-1 alloy, that just proves you are using good technique with your Lee tester ... which uses the Brinell method to measure hardness, and produces results in actual BHN values.

Press on ...

CM

I'll pass along your kudos to a friend who did the measurements for me. I do not have the money to purchase a Lee tester at this time, and probably would not try due to the nature of the "industry". Just too painful to wait for back orders...

[ColColt]

I know with smokeless loads you base alloy on chamber pressure. With BP I don't know. Maybe a bit of experimentation may be in order.

[huntrick64]

OK, first of all, I am a NOOB at BPCR, but I have been casting for a while and hunting with cast that same amount of time. So now that my disclaimer is out of the way, BHN is only one factor (or characteristic) in a cast boolit. If BHN is the only factor that matters in whatever you are doing with the boolit, then no matter how you get to BHN 10, you will be at BHN 10. But think of this, remember trying to share taffy with a buddy? If you bent it slow, there was no way you were getting it apart. Bend it fast and it snaps in two pieces. Now you could find another candy that will bend slowly with the same resistance as taffy, but would not snap in two due to other characteristics.

Another way to put it, for most of my life I have been exactly the same height and weight as Mike Tyson. Take my shirt off and stand me next to him and you would not get us confused!!! Nuf said bout that. :wink:

So, if you are hunting with cast, one BHN 10 boolit without antimony might shoot to the same POI as another BHN 10 boolit of an atimony mix, and it might lead or not lead exactly the same way. Hit an animal with the two boolits and the one with antimony might bust into pieces where the one without will probably flatten out, but retain most of its weight.

just my thoughts, your mileage may vary!

[John Boy]

3 parts Lyman #2 and 7 parts pure lead
Been mixing the 3 -7 alloy using 3 parts clip on weights with a Bhn 15.4 (close enough to Lyman #2).

[montana_charlie]

The "New Postel" that Steve Brooks makes has a slimmer nose than the old Postel. Would that be considered a problem with possible nose slump as mentioned?
The 'new' Postell is simply the version made popular by Ideal/Lyman. Treat it just like the original Postell. They both have 'strong' noses ...



Been mixing the 3 -7 alloy using 3 parts clip on weights with a Bhn 15.4 (close enough to Lyman #2).
The 3-7 alloy is valuable for it's stability ... not it's hardness, per se. According to DT, the stability is caused by the tin and antimony being equal parts of the mix. (1.5% each).

An alloy of 96/2/2 is equally stable, but a harder metal (approximately 10.3 BHN).

Your clip-ons have a lot more antimony than they have tin, so the long term stabilty factor may not be there.


CM

[huntrick64]

John Boy, are you water dropping the 3 - 7 alloy to get bhn=15.4? My straight wheel weights are only around 14 BHN if air-cooled? My 50-50 with these wheel weights is around 8-9 BHN.

[montana_charlie]

Many charts say that 20:1 alloy is made with 95% lead and 5% tin. This is 19:1. As you so apply stated, 20:1 would be 20 pounds of lead and 1 pound of tin, or 100 pounds of lead and 5 pounds of tin. Again, which is right for the "historical" alloy of 20:1. It cannot be both, so which did the ordnance department come up with in the 1870s or so: 95% and 5% (19:1 actually), or 20:1. Not much of a difference at all, so my argument does not stand on that problem. It is just more of a curiosity, since you brought up the point about the charts concerning the BHN of 20:1 alloy.
Frankly, I don't have a chisel sharp enough to split that hair.
A guy with one pound ingots would simply use twenty of one and one of the other.
A guy with a scale, might weigh out metals until he had the 19 and 1 mix.

I suspect that the "95/5" designation is more 'modern' than the "20 to 1" (20:1) label, so I would presume the 'old charts' ( those which do display '20:1') were based on twenty pounds of lead and one pound of tin ... all thrown in the same pot.

But, it IS a presumption, and the reality doesn't matter much when it comes to the tiny difference in alloy.

Later,
CM

[ColColt]

To add a little more fuel to the fire...per RotoMetals...

"1:20 has a BHN of 6.45 if you do the math correctly. These numbers often change based on the purity of metal your using, wheel weights, etc... This is why we do not sell based on BHN as it is very easy to incorrectly come up with a accurate BHN"

[montana_charlie]

To add a little more fuel to the fire...per RotoMetals...

"1:20 has a BHN of 6.45 if you do the math correctly. These numbers often change based on the purity of metal your using, wheel weights, etc... This is why we do not sell based on BHN as it is very easy to incorrectly come up with a accurate BHN"
That is one confusing statement.
If a company offers certified metals, then there should be no possibility of "change based on purity" in the alloys they sell.
But, if hardness results get based on "the purity of metal your[sic] using" then it would depnd upon the garage metalurgist ... not Rotometals ... because (they say) he might be using wheelweights.

What any of this has to do with certified 20 to 1 (or 1:20) is anybody's guess ... I guess.



As for the claim that 20-1 has a hardness of 6.45 BHN ... well, that is a 'calculated' value and I will illustrate.

They have this posted for all to use:

Basic Rules for Harding Lead-

For every 1% additional tin, Brinell hardness increases 0.3.
For every 1% additional antimony, Brinell hardness increases 0.9.
For a simple equation,
Brinell = 8.60 + ( 0.29 * Tin ) + ( 0.92 * Antimony )

First, assume that pure lead has a hardness of 5 BHN (it's really more like 4.5 but go with 5 for now).
Then make an alloy with tin at 5% of the mix.
Now, use the stupid formula and multiply 0.29 by 5(%) to get 1.45.
Add that 'hardness increase' to the original 5 BHN and Viola! you have 6.45 BHN.

Does anybody have time to go back and wonder why the '8.60' part of the formula got disregarded?
You might think that, since everybody knows that pure lead isn't that hard (8.60 BHN) it makes no sense to add 1.45 to that number.
But IF YOU DO run the formula as written, the hardness for 20 to 1 alloy comes out at (guess what?) 10 BHN!

That's the same value which has been in the 'old charts' for a hundred years.
The problem with it is that it's wrong ... and always has been.
It is probably a fact that all of the 'old chart' values for lead/tin alloys are 'calculated' or 'derived' numbers which were never based on actual hardness tests.

The 'old chart' numbers which ARE useful are those that got added for the newer alloys (like Lyman #2) which are actual, tested, hardness numbers.

Rotometals seems to have two opinions on the hardness of 20-1 because their description page for that product looks like this:

http://i684.photobucket.com/albums/vv203/montana_charlie/ScreenShot023_zps0f4f2769.jpg?


CM

[ColColt]

Rotometals seems to have two opinions on the hardness of 20-1 because their description page for that product looks like this:

Yep, 6.45 is not hardly "approximately BHN 10"

[40-82 hiker]

Yep, 6.45 is not hardly "approximately BHN 10"

I am coming to the conclusion that the most important part of this hardness testing is the documentation we use to check our results with. So, what is considered the "holy grail" of BHN values for boolit hardness values? This would include CORRECT values of the old mixes (e.g., 20:1, 30:1, so on).

[montana_charlie]

I am coming to the conclusion that the most important part of this hardness testing is the documentation we use to check our results with. So, what is considered the "holy grail" of BHN values for boolit hardness values? This would include CORRECT values of the old mixes (e.g., 20:1, 30:1, so on).
Again, it is the lead/tin alloys that can't be trusted in the old charts. Antimonal alloys might be listed accurately because they actually got tested in later years.

But, for the lead/tin alloys, this is what I gleaned from the 'researcher who remains nameless'.
Each of the alloys except the Lyman #2 age-softened to the listed hardness. The softening time varied between 12 hours (20-1) to 4 days (16-1).

The Lyman alloy probably age-hardened because that's what antimonal alloys do. But, how long it took to reach it's advertised 15 BHN is unknown to me, as is it's hardness immediately after being cast.

Certified Lead: 4.5
Certified Tin: 5.0
Certified 30-1: 6.66
Certified 20-1: 7.8
Certified 16-1: 8.2 for a year, then softened to 7.39
Certified Lyman # 2: 15.4

Now, y'all know pretty much everything that I know about this subject.

CM

[ColColt]

I got curious as to the hardness of a pound block of tin I ordered from RotoMetal about six months ago and according to my Lee tester, it read .096 which is BHN 5.2...pretty close.

[montana_charlie]

I got curious as to the hardness of a pound block of tin I ordered from RotoMetal about six months ago and according to my Lee tester, it read .096 which is BHN 5.2...pretty close.
The 'old charts' have tin listed at 7 BHN.

[Dumasron]

Assume there is a bullet design that has no variable other than hardness.
Q1. How much change in bullet hardness is required to change the impact point by 1 minute?
Q2. Does cast bullet weight correlate inversely to tin content?
Q3. How much weight variability adds up to missing a ram?

How does Rockwell "B" scale correlate to BHN?
Thanks

[John Boy]

John Boy, are you water dropping the 3 - 7 alloy to get bhn=15.4?Huntrick ... No. All the aged air cooled clip ons that I have made into ingot over the past 5 - 10 years have either been Bhn 13.5 or 15.4. I keep reading in the alloy calculation programs the WW's are Bhn 12. Close to 2000 lbs of ingots, have never had an aged batch at Bhn 12

[huntrick64]

John Boy ... Once again this faceless medium called "the internet" has tricked me! When I first read you statement:

"Been mixing the 3 -7 alloy using 3 parts clip on weights with a Bhn 15.4 (close enough to Lyman #2)."

I was thinking that your 3-7 alloy had a BHN of 15.4, not that your wheel weights used in your alloy had a BHN of 15.4. That was why I questioned how you got there, because I have never been able to blend a soft metal with a hard metal and end up with an alloy harder than the hard metal was to begin with. See my confusion? My bad.

Rick

[John Boy]

See my confusion?
Yep and I have them too. Happy that you got it sifted out. It is a good alloy combination IMO

[Boz330]

This may not correlate to anything useful but I borrowed a friends Cabin Tree tester and all of the different batches of WWs that I had, came out at the same as 20-1 on the tester. The second thing I found was that shooting WWs in my BPCR gave very good results for 10 to 15 rounds then went south because of leading. Another one of the guys I shoot with uses nothing but WWs and has no trouble from them. I stopped using WWs and the tester and throw 20lbs of pure with 1lb of tin in the pot and cast. I don't weigh just throw 1lb Lyman ingots in the pot. It varies a little bit on weight but I figure that I can't hold it better than that anyway.

Bob

[cajun shooter]

First thing I would like to interject into this thread is that all of the newbies need to go to the sticky section. Look for the book written by Glen Fryxell and Ron Applegate. It is called From Ingot To Target. It is about 172 pages in length and and it would be of great value for the rest of your life. Glen and Ron combined probably know more about the art of casting and shooting than most forum members. They could of easliy published this book and made a hunk of money but gave it to this forum for free. I printed it out and put it in a 3 ring binder. I started casting and reloading in 1969 and I still have used the book many times.
Now as far as WW's go, John Boy and I have discussed this subject before. I live in South Louisiana and I have never seen a WW in this area that test much above a 10 BHN. I have found a few that go to 12 BHN but they are very rare.
I use a Cabin Tree tester as opposed to the Lee. The Lee has been found to give good results in Lab Testing conditions but I find flaw with this tool and the way a reading is taken. It all depends on how good your eyesight is for one thing. It also depends on you keeping the pointer rod flush with the top of a die for 30 seconds which most will screw up. Then last it gives you a chart to compare your results with the standard test sheet. It has a lot of areas left open for mistakes to be made. The Cabin Tree only requires you to line up two lines after giving the handle a 360 degree turn.
They gave the Lee to 10 persons in one test of it and each alloy tested was given 10 different readings.
For the new member who has yet to purchase a tester, save your funds and purchase the Cabin tree.
As far as alloy goes for shooting BP I'll just say go to the big shoots and see what the winners are using. I don't think you will find Lyman #2 as being very common or for that matter you m,ay not even find one shooter with it.
Besides reading the book by our two great members, you should also read the book by Mike Venturino by the name of Shooting Buffalo Rifles Of The Old West. It has a very respectable section of this nations top shooters giving you the information on what works for them. Take Care Fairshake