Lead-free bullet casting alloy

fiver

Well-Known Member
yep bashing it, or mashing it in a vise will show quite a bit.
I bet holding it in a vise and hitting it from the side will show something too.

I'm wondering how much like cero-safe this alloy will act.
I'm interested in the mash-ability, that would determine the speeds needed for terminal performance.
the application might not be really suited for straight naked use [shrug] ,,,,, BUT it might make a suitable core for a copper wrapped lighter bullet and that might be the ultimate application due to velocity necessities.
 

popper

Well-Known Member
Antimony-Bismuth Alloys
These metals form a continuous series of solid solutions, the liquidus curve lying wholly between the melting points of the two metals, and the solidus being practically horizontal between 0 and 60 per cent, antimony. Some evidence for the existence of Bi3 molecules has been obtained, and the anomalous form of the solidus curve has been ascribed to this. The hardness has been determined. The boiling point curve shows a maximum. These alloys have been examined by X-rays, homogeneity being obtained by prolonged annealing at 280° C. The lattice edge of the rhombohedral crystals varies almost linearly with composition.

Some data on the characteristics of these alloys. Interesting crystaline forms, S is a predominate characteristic.
 

CZ93X62

Official forum enigma
There is another idea at play here as this venture unfolds. Barnes Bullets has done a great job of rising to the occasion as far as common non-toxic rifle caliber bullets are concerned. They have even taken on the 22 Hornet, which pleases me in no small way.

Where Barnes falls short is "Covering older/obsolescent calibers". In my own sitch, 25/20 WCF, 30 Carbine, 32/20 WCF, 38/55 M&B, 44/40 WCF come to mind as candidates for 88/12 casting consideration. If we are going to chase niches, I think our effort should (at some point) cover ground not already cultivated by Barnes.
 

Ian

Notorious member
Swaging jackets and cores or paper patching is a niche of a niche, I mean there are probably a couple dozen of each in the whole country with the means and knowledge to do that. I have PP moulds for several calibers and can test that....but who else is going to follow?

If the Bi/Sn/Sb alloy is ductile enough to offer some expansion without shattering, it will likely shoot well too as a conventional lubricated bullet and work at higher velocities with a gas check. If it is too soft (I think the opposite will be the case), it can be powder-coated or possibly heat-treated.

We're looking at a an 8 bhn eutectic bismuth/tin solder alloy (58% Bi iirc) which with addition of half a percent antimony finds its grain size reduced by considerably more than 50%. 88/12 is supposed to be about 19 bhn and is also supposed to be the best compromise between brittleness and weight. People have been shooting it in rifles as-is with at least functional results. That tells me the antimony addition should only improve the the 88/12 and there is room for more tin if necessary to reduce the bhn and increase ductility at the expense of a little mass.

I think with bismith, tin, and antimony we have the means to make a funtional substitute which has the melt point, strength, mass, and ductility necessary to replace our ordinary bullet casting alloys if we can only fine-tune it and adapt to the metal's differences.

The last hurdle will be expense. We're looking at $15/lb for the replacement which is at first blush a complete show-stopper. However, for a little load development and and whatever is actually used for hunting, I think the expense to remain self-sufficient in this respect beats any alternative.
 

fiver

Well-Known Member
a core for a 150gr jacketed bullet weight about 116-118grs.
that's like 75 per lb [rough guess] jackets are about 10 cents each.
a box of 150gr 30cal. sierra's at the store is 30$ [plus tax] so for 32$ worth of material...

I'm imagining the weight is less than lead by 25-30$ so you'd actually have a greater volume and could get more bullets from the alloy.
it would also be super simple to bond the core to the jacket with that much tin in the alloy.

the only 2 things I'd be really worried about is the high tin percentage would be damn rough on the swage dies.
and it would also provide penetration like an armor piercing bullet.
they only used like 3% tin in WW-2 AP bullet cores, not really an apples to apples comparison because of the jacket composition etc.

I think it might be possible to go straight from the anneal to lube to point forming before the alloy was completely cooled off and save a lot of the stressors to the equipment.
 

RBHarter

West Central AR
I have a 301618 in AL . A couple of HB moulds too .
Last I have a HP 100-110 gr 30 cal swage die set . I've not set it up but it's all there although I don't have the tools to make the short or full jackets I also don't have any . Perhaps a few 5.7 cases ?
 

fiver

Well-Known Member
Allen.
if this can be done, I have the means to do 44 cal jacketed bullets.
I'd need some machinist help to pull off 32 or 30 carbine though.
I have a 30 carbine swage die for short jackets but I'm missing the top punch.
however I believe I have 4-500 jackets still.

yep 5.7 cases will work.
I have a push through die for sizing them down for 30 cal [it's .304] but then they need bumped back up in a core seat die, and a final bump in the 308 die.
25-20 jackets can be made from 25 acp brass easy enough but I ain't got those tools.
38-55 jackets ain't too hard to make from 3/8th's tubing and it can also be made from pushing down long 9mm types of brass.
 

CZ93X62

Official forum enigma
Swaging is an option (my point of view) only if conventional casting and cast bullet processing is an epic fail. We also need to look at costs/benefits trade-off with just buying Barnes Bullets for the common calibers. I am willing to try the rabbit hole, sure--but I don't want to make it a full-time residence. While California and the rabid Center For Biological Diversity are enamored with the non-toxic bullet delusion, other states look at the results and kinda shake their heads--per my DFW sources. They don't see this fetish spreading beyond California, and there has been some talk about rolling it back. Airguns for hunting are not required to go non-toxic, and Prometheus pellets have been around longer than has Barnes Bullets.
 

Ian

Notorious member
There is one other durable and 50-state reason to look at bismuth/tin alloy. Remember the zinc uber-high-velocity handgun ammunition that was once imported by (iirc) Aguila? We can make it with Bismuth and actually be able to cast the stuff with normal moulds.
 

CZ93X62

Official forum enigma
The Barnes all-coppers get up some nutzo velocities--4300 FPS in 22-250, 2300 FPS in 45/70 Marlin 95s. Keep in mind that my education was social sciences......the sectional density/specific gravity of the 88/12 alloys seems to run close to that of the Barnes all-coppers.
 

Brad

Benevolent Overlord and site owner
Staff member
Man, you would think Rotometals would know it is Sb.
 

Ian

Notorious member
Well, I stole ten minutes from the needy everything around here and took the ingots to the shop. First test was see how far I could bend one before it broke. Put it in a vice and stuck a bug Crescent wrench on it, didn't take much effort to snap it in half with apparently little flex. Probably not as strong as 1/2" plate glass put to the same test.

Next thing was dent it with a punch. It did show signs if deforming without fracturing to a point, but once that point was exceeded the ingot began cracking straight through.

Look at the huge grain formations, it appears that the antimony isn't doing a very good job of breaking that up like I had hoped.20191121_211815.jpg
 

Brad

Benevolent Overlord and site owner
Staff member
Are you intending to try both HP and solids?

Looks at first blush like a good solid, low velocity alloy. Good in 45-70
 

fiver

Well-Known Member
looks like lino-type in there.

did you hear any creaking or cracking when you were bending it?
 

Ian

Notorious member
It was a clean snap, no crying, no gristley noises, just a metallic pop.

Hit some with a hammer a bit ago and it can be deformed a bit and then it just explodes. I think it will shoot just fine (has enough give or micro-crush to stay together after being engraved) but it might not stay together when it hits anything more substantial than a blade of grass. Explosive qualifies "expanding", right? I bet this stuff would make some serious varmint grenades, might be pretty good actually.

Next thing was to take a 60 grain chunk of the Bi/Sn/Sb alloy and add 20 grains of pure tin bar to it and let it air cool to just solid in the spoon and then plopped it on a towel. After it reached room temp I put the blob on the anvil and whacked it with hammer and center punch, it split and both halves shot across the shop, leaving some fine granules on the anvil, much finer than the original alloy which would fracture down to about 1/16" grains.

The tin addition refined the grains considerably but didn't improve the brittleness a whole lot, but maybe some.

20191121_220629.jpg

I tried carving on the broken edges of both alloys with a sharp knife and the stuff won't slice, the blade just splits off little fragments.
 

Ian

Notorious member
so far what I'm seeing is the antimony is going to act like copper would in a Sb-Pb alloy.
I still can't help but feel something else is going to be needed to smooth things out so the alloy can flow under stress.

Both your analysis and your prediction appear to be spot on at this point. I'm going to try and cast some bullets next and shoot them. Getting gas checks to stay on might be a challenge due to possibly crushing the shank when sized, but I have soft aluminum ones in three calibers so might get around that. Kawasaki green powder coat will cure at 350⁰F no problem and I might go straight to that for the rifle stuff, we'll see.

My overall impression at this point is the extra tin addition made this stuff just about like linotype alloy.
 

Tom

Active Member
I don't understand half of what I've learned from others regarding alloys, but would a touch of copper toughen it up like it does with pb/sb?