HARDENING PURE LEAD

[steamjohn]

I have been casting bullets for my 45/70 using new roofing lead (sold as 99% pure lead). the hardness being below the value registered as 'hard cast' 15.4BNH on my hardness tester,

I decided to try and increase the hardness following the advice on the literature enclosed with my Lee Lead Melter i.e. add tin 10% and antimony 5% to increase hardness to BNH 16.0

The Lee Pot stated a maximum temp attainable is 483 C and antimony melting point is 630 C . Looking at various posts by casters attempting this process, it seems that the best way of achieving mixing of lead / antimony is to melt the antimony separately and then pour the liquid antimony in the molten lead and stir.

The resulting mixture poured into my Accurate Mould successfully but oddly the sprue plate required only very light gloved pressure to swing clear revealing a fully filled square based bullet. As the bullets fell from the mould they had the usual shiny finish but within 30 seconds or so they acquired a matt grey finish,

Another result of the modified lead mix was that the bullets weighed around 15 g lighter than the pure lead rounds.

In spite of fluxing with beeswax the process produced a huge quantity of light brown dross with a sandy texture.

It remains to be seen how they shoot compared with the pure lead.

Any comments/observation from members would be appreciated

 

[Dusty Bannister]

That is a very unusual alloy and also quite expensive to make. Generally, you will not need that much tin and the hardness you quote for pure lead being 15.48 BHN is even more confusing. Perhaps, since you are using Celsius measurements, you are not in the US and this could just be a language misunderstanding.

 

[Bret4207]

Pure lead Bhn is nominally around 5.0. Not sure what kind of tester you're using, but there's a problem if that is in fact 99% pure roofers lead.

I would also offer that jumping on the Bhn bandwagon, eg- the idea that HARDER has to be BETTER!!!, is wasted effort, time and $$$. Fit is King in cast, and it's a pretty far ranging and often involved process.

 

[Petrol & Powder]

I think there may be so errors or miscommunication in the first post.

starting with 15.4 BHn.
And the results of the hardness tester.

So, to the OP, can you clarify your statements please?
And I see temps in Celsius (that's fine, just checking on which scale you are using) and weights in grams (again, OK, just want to make sure we are all on the same page).

 

[Rick]

Should not mix a higher percentage of Sn than Sb. That much tin will not be a fun job removing it from the barrel.

Your desired mix will be fairly close to Linotype, what are these bullets to be used for?

What temp are you running the pot? Frosting over that quickly could be Sn oxidizing from too high a pot temp.

If this is the alloy you really want to use alloying Pb and Sb is incredibly easy using Roto Metals Super Hard. 60% Pb and 40% Sb, it's already blended for you. Using straight Sb can be a very dangerous thing, Sb is very toxic on it's own.

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Beeswax is not flux, it cannot flux. It is good for reducing but fluxing? Nope.

http://www.lasc.us/Fryxell_Book_textonly2.pdf

See chapter four On fluxing.

Of course your alloyed bullets are lighter. You added two metals, both of which are far lighter than pure lead.

 

[Dusty Bannister]

Steamjohn, it is not that we are trying to over load you with information, but just trying to find out your level of knowledge and where you are starting this journey. Too much new information all at once can be worse than no information at all. Maybe you could update your profile to just give a general location where you are. If outside the US, then references to Rotometals as a source is not an option. And the more helpful the suggestions and comments will be.

 

[steamjohn]

Thank you all for your comments and advice, I hope I have answered some if not all of your questions below.

Dusty Bannister I'm afraid you misread my opening sentence, I said the pure roofing lead I use is reading well below the figure of 15..4 which is quoted on factory made bullets, sold as 'hard cast' (by no means pure lead). I am presuming factory made bullets are cast to that degree of hardness for a good reason and wanted to try and emulate the round only in a mould of my design.

Yes I am in the U.K. and I simply changed the Lee Mould data to Celsius to equate with the figure quoted for antimony in Celsius. I could just as easily have changed the antimony figure from C to F.

Lee quote pure lead as 8.6 BNH with 0.29 Tin and 0.92 Antimony.

The factory made 'Hard Cast' grease groove bullets shoot quite well but I am experimenting with Powder Coating and Hi Tek coatings and that obviously does not require grease groove bullets, hence my having a smooth bullet mould made by Tom of Accurate Moulds.

The amount of tin and antimony I added to the pure lead was based on the figures taken from the Lee Mould data sheet. I merely assumed Lee knew what they were talking about.

I am running the pot hot, although brand new I am not sure the control is very precise and I'm told mix temp is not as critical as that of the mould. I am unable to accurately monitor the mix temp. while casting.

I built my own tester and used a factory Hard Cast bullet sold as 15.5 BNH as a datum.

The bullets I cast using the Lee data regarding adding tin and antimony, test to almost the same hardness as the factory hard cast rounds which was the object of the exercise.

I quite agree that fit is important and will experiment with sizing, after Powder Coating to .458", and shooting as cast which is .002" or more over. after the Powder Coat is added.

I am shooting a Pedersoli Sharps 45/70

I am quoting Gram not grain

In the UK were are not as well served in respect of home loading supplies as in the U.S. i.e. Roto metals, Lyman alloys etc.

The proof of the pudding will be in the shooting which may be somewhat delayed as we are having high levels of rainfall here and our range is flooded.

My post was mainly to enquire if anyone had had a similar reduction in bullet weight following on an increase in hardness. The reason has been pointed out by Rick.

 

[fiver]

woah,,, there is so much wrong going on there i'm not sure where to start.
as far as the antimony thing ummm,,, just no.

you can mix antimony crystals into a lead alloy that contains a little tin at @600-F.
the key there is to break the surface tension so the antimony can make good contact with clean alloy.
a little wax can do the trick as will a very small amount of something like marvelux and a very small amount of antimony at a time.... with a lot of stirring.
be prepared to make an afternoon of it.

trying to get it to simply melt in a LEE pot will pretty much end up with you having a burnt out pot... unless you have about 10 bs. of the stuff.

that brown dross you mentioned was oxidized alloy of one sort or another, i'm guessing all your tin first and then a ton of lead next.

 

[462]

Betcha' the U. S. Army and the buffalo hunters' .45-70s didn't use bullets that hard. I use straight wheel weights, in my .45-70 Pedersoli rolling block (guessing maybe 13 or 14 BHN?, because I don't know).

I don't paint my bullets, so have a question. If you paint your bullets, why can't you cast them of pure lead?

 

[steamjohn]

Dusty,

Thank you for your kind words.

I am 86 next birthday, served 17 years in the Navy flying choppers and fixed wing then a Master in the Merchant service. have been shooting rifles, shotguns and revolvers and pistols since my schooldays when the family .22" Martini (converted from a Boer War vintage .303" service rifle) was kept behind the kitchen door so as to be handy if any four footed or winged food showed itself. (food was rationed in England until well after WW II.)

How things have changed.

Now I mainly shoot paper with a variety of mainly historic guns, muzzle loading and cartridge. Shooting my two Lee Enfield .303 Rifles sparked an interest in loading my own ammunition, both for my Winchester .357" U.L., my two .303s and .357" long barrelled revolver.( Normal 8" barrelled revolvers are only allowed if they are Muzzle Loaders) and casting bullets for my Parker Hale built .451" Volunteer. My latest acquisition is a Sharps 45/70 which I fitted with an aperture sight initially and later with a replica Malcolm scope, same length as the 32" barrel. (eyesight is not what is was).

Apart from time on the range (Bisley is a 2 hour drive each way) or our local 50 yds range, my interest is in home loading / casting and experimenting with the the many variables that constitute a satisfactory round. Not made any easier in the U.K. by the lack of supplies, powders, primers etc. ( Unique which I found worked well in the Sharps with Federal Magnum Large Rifle Primers is now unavailable as are the primers) so I am now faced with beginning all over again with a different powder/ primer etc. Lead is either scrap of an unknown quality / purity or new roofing lead. Factory made bullets are available but are expensive, limited in variety and all grease grooved. It is said the Sharps was designed for paper patched bullets, (the rifling is 002") which I am experimenting with and that is another reason for playing with a plain as opposed to to a grooved bullet. As to hardness time and shooting will tell I think.

 

[JonB]

SNIP>>>

Another result of the modified lead mix was that the bullets weighed around 15 g lighter than the pure lead rounds.

In spite of fluxing with beeswax the process produced a huge quantity of light brown dross with a sandy texture.

Your antimony blending technique makes me think that the sandy texture is unblended antimony.
.
As to being lighter weight, Yes a Lead alloy with tin and antimony will cast a lighter bullet, than pure, or near pure Lead. You mention that you are meaning "grams" in a succeeding post. BUT here, I really hope you mean 15 grains lighter, which sounds about right for the alloy you probably ended up with ...because google tells me 15 grams is 231 grains.

 

[Petrol & Powder]

steamjohn , thank you for the clarification.

Yes, pure lead is far below 15.4 BHn in terms of hardness.

A reduction in weight with the addition of tin and/or antimony is to be expected due to the decreased density of those alloys as compared to pure lead.
15 GRAMS lighter (as opposed to 15 grains) is a lot, 15 Grams total (as opposed to a 15 gram difference) seems a little more in line with what we're talking about.

The temps aren't really important, the mold will tell you where the temperature needs to be.

And yes, you folks are getting hammered with rain right now, but I see that northern Sweden is currently -40 C which conveniently corresponds to -40 F. So, you got that going for you.

 

[Bret4207]

Steamjohn, couple points to consider-

"Fit" is not simply sizing diameter. Fit comes in 2 parts- Static and dynamic. Static fit involves sizing diameter, position of the bullet in case, crimp or not, getting the case/bullet concentric in the chamber/throat, etc. IOW- everything that comes before the primer is hit. Then dynamic fit comes into play, getting the bullet to play nice with the barrel and hit the target after being mashed with a bunch of pressure.

I would not put much trust in Lees cast bullet recommendations...period. They make some good equipment that the average man can afford, but there are limits to their veracity when it comes to cast.

The main reason "HARDCAST" bullets are out there is to minimize damage to cast bullets shipped in bulk containers. No one like spending $ on something and having it arrive beat up and dented, which is what will happen with common shipping boxes and, say, 500 bullets being thrown around by the gorillas in our shipping services. Same for the crayon type "lubes" adhering to the hardcast bullets. It's not that it's great lube, it's that it will stick to the bullet in shipping. The various commercial hardcast bullets rarely shoot as well as home cast once you start getting the hang of things.

ETA- Why do you want to harden your lead for a 45/70? Soft alloys usually work very well in them, including pure lead.

 

[STIHL]

For your Lee pot, and this is just a rough way to do it, not scientific by any means. I run my pot at 10 until the alloy melts, then I back the dial off to 7 ish, and adjust from there. Depending on ambient temperature and alloy level I may increase it a little, but most of the time decrease it as I go. I sometimes end up around 5 on the dial as the pot empties. I have a Lyman thermometer I stick in occasionally and it has to be off because if I run it in the7- 750 F range it will not cast for anything. Fill out is horrible, if I keep it around 850-900 F we are in business. I don’t trust the temp reading, I use it more as a visual indicator of what works for me and to attempt to keep my molds running in that sweet spot to my rhythm. I’m using a trash alloy that is very close to COWW and good clean COWW alloy and they both cast almost identical, hardness ends up at 11-12 BHN after casting but will harden to about 15 BHN after a few weeks after 3-4-5 years I just checked some and they are 20BHN.
I quit worrying worrying as much about hardness when I realized it was a factor that is ever changing. After meeting these fine folks here I learned more about casting than I ever dreamed and realized the good old BHN was not as important as I was originally led to believe, and I needed to focus on more important things. This has not been that long ago. I’m not saying that there is never a need for a harder or softer alloy, but for all the shooting I have done thus far, my trash alloy has been ringing steel for several years now and has made me smile many days.

 

[Rick]

I gave up completely on mechanical thermometers many years ago. I had/have three, with all of them in the pot at the same time I couldn't tell the pot temp within 100 degrees. The PID I sort of trust and is all I ever use any more.

 

[popper]

Pot temp should be ~400C. Way too much tin. Add another 20 pounds of your roofing metal to 10 pounds of your alloy. Gets you about 2% tin. Then add your Sb to that alloy to get 2%. The antimony will slowly melt/dissolve into the alloy, NO need for the extra high temp in the pot.

 

[358156 hp]

If it helps at all, the old time black powder lead/tin mix appears to be 16:1, which is about 11 bhn. Your side of the world may have had a different spec.

 

[BudHyett]

My experience with .45-70 alloy choices:

• Black Powder: 20:1 Pb/Sn with SPG Lubricant sized in a .460 die after dropping .459 from the mold.
• Smokeless Powder: 92/6/2 Pb/Sb/Sn with NRA Alox Lubricant sized in a .460 die after dropping .459 from the mold.

I own several .45-70 rifles plus a Winchester 1876 in .45-60 and this is my collective experience. The molds I'm currently using are the SAECO 1881 500 grain Government bullet for black powder, the RCBS 45-325-FNU (.45-60), and RCBS 45-300-FN for smokeless powder. More than 2% Sn is a waste.

Note: From your description of the melt, you might have zinc contamination which fluxing with resin will clean out.

 

[Rick]

I used 2% Sn for several years, then being the curious type I went up to 3% Sn, I learned one thing, my Sn disappeared faster, right about 33% faster.

 

[Petrol & Powder]

If it helps at all, the old time black powder lead/tin mix appears to be 16:1, which is about 11 bhn. Your side of the world may have had a different spec.

I was going to suggest something around 11 BHn or 16:1 but held off giving that input. However - I completely agree with this /\