School me on lead alloys

[HammerMTB]

I just got a Sharps replica, and will cast some boolits for it. I could make any alloy I want- I have the materials.
Why do some use 40-1, some 30-1, and others 20-1? Is there some advantage to more tin?
Tho I have not tried the alloy, I can cast well filled out boolits of pure lead for my ROA and muzzlestuffer. Can't imagine the .45 cal boolits to be any different.
So, what do you use and why? I'd love to hear form the more experienced...
and since I have yet to bust a cap on this 1874, pretty much all of you qualify as more experienced! :bigsmyl2:

[Lead pot]

The alloy I use is based on the type of bullet. The longer the ogive the harder I make the alloy.
Take the top left bullet, it has a very long sharp ogive. This bullet needs a fairly hard alloy so the nose does not slump or bend when it is fired. That particular bullet I cast with 1/16 or #2 Lyman.
second on top it has a shorter ogive radius and it will stand better so it is cast with a softer alloy like 1/18 or 1/20.
Bottom bullet has a short blunt ogive almost a round nose and it will stand with a very soft alloy like 1/40.
All three can be cast with the same 1/16 but not with 1/40.
This is about as simple as I can explain it.

http://pic20.picturetrail.com/VOL1337/6360369/22902670/389906322.jpg
http://pic20.picturetrail.com/VOL1337/6360369/22902670/389906323.jpg

[HammerMTB]

The alloy I use is based on the type of bullet. The longer the ogive the harder I make the alloy.
Take the top left bullet, it has a very long sharp ogive. This bullet needs a fairly hard alloy so the nose does not slump or bend when it is fired. That particular bullet I cast with 1/16 or #2 Lyman.
second on top it has a shorter ogive radius and it will stand better so it is cast with a softer alloy like 1/18 or 1/20.
Bottom bullet has a short blunt ogive almost a round nose and it will stand with a very soft alloy like 1/40.
All three can be cast with the same 1/16 but not with 1/40.
This is about as simple as I can explain it.


I wondered if it could be related to slumping.
So, is there something wrong with some antimony for hardness? It certainly can't hurt the barrel. Is there just more period specific "purity" to using lead-tin only?
Kind of like using BP only and not smokelees?

[montana_charlie]

So, is there something wrong with some antimony for hardness? It certainly can't hurt the barrel. Is there just more period specific "purity" to using lead-tin only?
It may be the 'purist' view that has made lead/tin so universal among BPCR shooters, many of whom display a distinct aversion to antimony.
I picked it up as well, and considered antimonal alloys as 'unsuitable'...until recently.

Lead Pot's top left bullet is a paper patch version of the Money bullet designed by Dan Theodore. He (Dan) usually has recommended the 16 to 1 alloy for this bullet because of it's fairly slender nose.

BUT, he has just spent most of a year testing alloys to see how stable they are...hardness-wise. One of the results he has felt useful enough to pass on to us involves an antimonal alloy he has concocted.

Dan's currently recommended Money bullet alloy is what he calls the "three-seven alloy". It is 3 parts Lyman #2 and 7 parts pure lead.
This results in a content of 97/1.5/1.5 (lead/tin/antimony) and is 8.2 BHN when cast. After 18 hours, it stabilized at 9.8 BHN, where it stayed for a full year.

Apparently, it closely approximates 16 to 1, but the antimony seems to increase it's ability to reach..and stay...at a stable hardness.

If you are using a bullet which fits your groove diameter well, it won't need to 'bump up' to obdurate the bore. In that case, this antimonal alloy would probably serve you well for any bullet design, and you would benefit from the stability of it's hardness.

CM

[Lead pot]

I feel antimony has a place with bullets, I use it in some of the bullets I shoot.
Mostly I shoot a bullet like in the bottom photo patched to .003 over bore diameter and the alloy is just about straight lead 1/40 mostly and it shoots very good.
I will say this what I see using antimony. With #2 Lyman the bullets don't have the knock down power that a soft bullet has when I shoot at silhouette targets like the rams, they don't go down as fast even when I use the .50 2.5. They just lay over when they get hit with a 1/30 or 1/40 they will get knocked back several feet. The antimony seems to make the bullet brittle and they fragment on impact and don't have the knock down power that the soft bullets have.

[kennisondan]

read with great interest my thanks too.
dk

[Don McDowell]

20-1 is a pretty good place to start with the vast majority of bullets.

[Boz330]

The antimony probably doesn't make much difference in a PP boolit other than what Lead Pot found which does make a lot of sense.
My high wall would lead like crazy with WWs and be completely inaccurate by the end of a 40 round match. The lead tin mixes never give that problem. The kicker is that several of the best 10 round groups that I have shot through that gun were with WWs. I never tried the WW pure lead mix. Now I have a good supply of pure where I used to have more WWs. As Don pointed out though 20-1 is a good place to start and see what your gun likes.

Bob