Lead-free bullet casting alloy
- Thread starter Ian
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CZ93X62
Official forum enigma
Given the alloy's behavior as you describe it, a 223 Rem bolter would be a good crucible for initial testing. Smaller caliber bullets are the most daunting and exacting to cast well, so we will give the alloy a "Worst-case scenario" tasking for its initial pour-dynamics test-drive.
One of the concerns I have as I ponder your observations is that if impact forces downrange can cause explosive effects--I wonder what effects that tons of pressure shoving the material downbore into rifling will have on the castings' structural integrity, and upon the barrel metal. I would do a good bore check after each shot right at first.
One of the concerns I have as I ponder your observations is that if impact forces downrange can cause explosive effects--I wonder what effects that tons of pressure shoving the material downbore into rifling will have on the castings' structural integrity, and upon the barrel metal. I would do a good bore check after each shot right at first.
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fiver
Well-Known Member
Tom.
copper is kind of on my mind also, but my gut is telling me it would be something else.
the Sb addition should have acted somewhat like copper does in a normal Pb type alloy.
the problem here is that lead doesn't break down into finer crystalline structure, it just mushes and flows around.
Bismuth and antimony both have different crystalline structures that break and separate leading to the fragmentation.
now Tin in small amounts will act as a grain refining agent in a normal alloy, so does arsenic.
they pack down the structure tighter.
that is the kind of thing necessary here [funny,, the solution would be lead or gold] there just ain't really anything else economically feasible you can add to the mix to make that happen.
I have been leaning towards the swaging aspect just to break everything down and compress it before trying to add any stressors, unfortunately the high tin content might not allow that to happen.
but like I mentioned,,, as a highly fragile core in a thin jacket... wow.
even a highly cushioned start might still not allow 100% accurate shooting due to some chipping or internal stressing of the bullet itself when it's shot naked.
copper is kind of on my mind also, but my gut is telling me it would be something else.
the Sb addition should have acted somewhat like copper does in a normal Pb type alloy.
the problem here is that lead doesn't break down into finer crystalline structure, it just mushes and flows around.
Bismuth and antimony both have different crystalline structures that break and separate leading to the fragmentation.
now Tin in small amounts will act as a grain refining agent in a normal alloy, so does arsenic.
they pack down the structure tighter.
that is the kind of thing necessary here [funny,, the solution would be lead or gold] there just ain't really anything else economically feasible you can add to the mix to make that happen.
I have been leaning towards the swaging aspect just to break everything down and compress it before trying to add any stressors, unfortunately the high tin content might not allow that to happen.
but like I mentioned,,, as a highly fragile core in a thin jacket... wow.
even a highly cushioned start might still not allow 100% accurate shooting due to some chipping or internal stressing of the bullet itself when it's shot naked.
Ian
Notorious member
Let me side-track a minute here.
We know how Linotype alloy shreds under stress and can't be shot accurately at HV in normal twist rifles due to the brittle alloy rubbing off on the drive side of the engraves. This Bi/Sn/Sb alloy will be much the same if not a lot worse in that respect, so I'm considering powder-coating the .223 bullets from the start just to give a flexible layer and hopefully keep the crunched dust from the bullet surface from shedding. If I can't push these to 3K fps then there's not much point in even bothering to make them IMO. Powder coating will also give me a chance to normalize the alloy after applying gas checks and sizing. For larger calibers and lower velocity I'm not really concerned about the engraving abrasion right now, will do conventional lube testing first with those.
We know how Linotype alloy shreds under stress and can't be shot accurately at HV in normal twist rifles due to the brittle alloy rubbing off on the drive side of the engraves. This Bi/Sn/Sb alloy will be much the same if not a lot worse in that respect, so I'm considering powder-coating the .223 bullets from the start just to give a flexible layer and hopefully keep the crunched dust from the bullet surface from shedding. If I can't push these to 3K fps then there's not much point in even bothering to make them IMO. Powder coating will also give me a chance to normalize the alloy after applying gas checks and sizing. For larger calibers and lower velocity I'm not really concerned about the engraving abrasion right now, will do conventional lube testing first with those.
fiver
Well-Known Member
that's not really a sidetrack.
think about it like this.
you have to get the alloy to cast.
you have to figure out the timing of getting the bullet out of the mold [this could be a problem]
you have to predict what the bullet is going to do over a period of time.
size-lube
load
shoot.
each step is going to pose a problem of some sort, and there will be limitations.
think about it like this.
you have to get the alloy to cast.
you have to figure out the timing of getting the bullet out of the mold [this could be a problem]
you have to predict what the bullet is going to do over a period of time.
size-lube
load
shoot.
each step is going to pose a problem of some sort, and there will be limitations.
Ian
Notorious member
I already made a basic properties test checklist sort of like the Apollo flight rotation (one test may or may not lead to more of same before progressing) and a detailed list of calibers, moulds, and firearms based on the expanding property of the alloy and ability to size down (or not). It can get pedantic so I spared a lot of the details. I already axed about 2/3 of what I was going to do when I broke the first ingot.
fiver
Well-Known Member
chuckle.
like that old saying.
everyone has a plan till they get punched in the face.
re-focusing on the 22 cal varmint strafing ammo is probably a good direction to focus your efforts.
and IMO adding in the P/C is gonna help work around some of the other issues you'll face.
you know a jump will probably be a benefit.
neck tension needs to probably be lightish.
the 'problems' will probably work out many of the details for you.
like that old saying.
everyone has a plan till they get punched in the face.
re-focusing on the 22 cal varmint strafing ammo is probably a good direction to focus your efforts.
and IMO adding in the P/C is gonna help work around some of the other issues you'll face.
you know a jump will probably be a benefit.
neck tension needs to probably be lightish.
the 'problems' will probably work out many of the details for you.
Ian
Notorious member
This is for hunting, so I see no reason to mess with auto-pistol calibers except maybe for funsies.
The nature of the alloy makes it look like .30-caliber is not going to be very effective except on critters other than "big game" as defined in CA, so that leaves the slow big bores such as .45/70 and maybe .45 Colt/.44 Magnum with WFN/RFN bullets as the only other general area to cover, and there is the "expanding nose" caveat which might be a grey area.
I'll start with trying to cast, gas-check, and size .223 and if that works what I learn from shooting should translate up to .30-caliber and anything in between pretty easily. I hope this will work as an ordinary lubricated cast bullet but I suspect the velocities will have to be kept fairly low. We shall see...
The nature of the alloy makes it look like .30-caliber is not going to be very effective except on critters other than "big game" as defined in CA, so that leaves the slow big bores such as .45/70 and maybe .45 Colt/.44 Magnum with WFN/RFN bullets as the only other general area to cover, and there is the "expanding nose" caveat which might be a grey area.
I'll start with trying to cast, gas-check, and size .223 and if that works what I learn from shooting should translate up to .30-caliber and anything in between pretty easily. I hope this will work as an ordinary lubricated cast bullet but I suspect the velocities will have to be kept fairly low. We shall see...
Ian
Notorious member
Rubber meeting road now. Casting is different but nothing too exotic. The big bullets take 3-4 minutes to cool sufficiently to shuck from the mould or they grow warts. .30 caliber (it was so easy I got bored and cast some) pretty much all grew warts even waiting two minutes between pours. The .22s cast perfectly from a cold mould but like all of them shuck a little more easily as the mould heats up some. Once they start shucking easily...slow down because the bullets are crunchy on the outside and liquid on the inside and expand as they continue to solidify and push liquid out in blobs here and there. On average I got .001 to .002" larger than with wheelweights and a warm mould throws a thousandth bigger still. There are a lot of other things to mention about casting but we'll get into that later.
Ian
Notorious member
Now for the smash tests. The bullets have a certain squish tolerance and then they crack and explode. After blowing up one of the .45s with half a dozen hammer blows I did another right up to the limit without cracking it and you can see how the whole bullet crushed down proportionately. The .30 caliber took one blow too many but you can see the deformation before it gave up and split. I also sized a few and they do just dandy squeezing down .003".
Ian
Notorious member
I'd have ro reference the phase diagram to see which thing is solidifying last. This isn't eutectic alloy, there's a nice mush phase but the thermal conductivity is weird and it takes a long time for the cores to cool.
The grains are huge but the initial bit of deformation is very smooth before major fractures appear. You know how wheelweight metal will kind of look bubbly on the surface as it is squished? This is as smooth as pure lead...until it flies apart. I do think the antimony is working now because the photos of other smashed or recovered bullets I've seen from the 88/12 appear to just shatter with almost no deformation.
There is just about zero springback after sizing, so a larger die will be required than normal.
Here's one of the .22s after running into my tapered in-out die. The stiff, 18.6 bhn alloy sizes nicely with no lube and can be ejected without swelling the nose. I'm pretty excited to try these out, maybe tomorrow.
The grains are huge but the initial bit of deformation is very smooth before major fractures appear. You know how wheelweight metal will kind of look bubbly on the surface as it is squished? This is as smooth as pure lead...until it flies apart. I do think the antimony is working now because the photos of other smashed or recovered bullets I've seen from the 88/12 appear to just shatter with almost no deformation.
There is just about zero springback after sizing, so a larger die will be required than normal.
Here's one of the .22s after running into my tapered in-out die. The stiff, 18.6 bhn alloy sizes nicely with no lube and can be ejected without swelling the nose. I'm pretty excited to try these out, maybe tomorrow.
