lead hardness
- Thread starter Gitsum
- Start date
I work in a lab and it was in an old piece of equiptment to keep it from moving. It was getting replaced and on the way out myself and two others grabbed up all of the lead to use for river decoy weights. It works great but the hardness is not an issue for that. For boolits I would like to know if this will work as is or if I should find out how hard it is. I want to use it mainly for 38spec and 9mm range ammo.
In general, hardness affects how easily the bullet is upset by pressure. You usually want a little bit of upset to help the bullet obturate (seal off) the bore. Absent a seal, gas escapes around the bullet, cutting and splattering lead in the bore so that it builds up quickly and starts to spoil accuracy. If the bullet is too hard it upsets little, and that means that if it doesn't start out over bore diameter it will tend to remain undersized, even under pressure. If the bullet is too soft it can upset too much, filling the chamber throat or a revolver forcing cone to a degree that can actually raise pressure over what a harder bullet would give you with the same load. It also means the bullet is overly distorted and that tends to be bad for accuracy. Also, softer lead shaves off a soft easily, so bore roughness is more prone to cause leading with one if it is fired at too high a pressure.
An old rule of thumb is to multiply the BHN of your alloy by 1422 to get the minimum operating pressure for best obturation, but if your bullet is a couple thousandths oversize, then, even if too hard, it still seems to shoot.
An old rule of thumb is to multiply the BHN of your alloy by 1422 to get the minimum operating pressure for best obturation, but if your bullet is a couple thousandths oversize, then, even if too hard, it still seems to shoot.
Missouri Bullet Co has this really cool formula to set a goal for BHN for a particular recipe. What unclenick is saying but using the velocity and pressure rather than the other way around.
http://www.missouribullet.com/technical.php
http://www.missouribullet.com/technical.php
I did some experiments with a Ruger Super Blackhawk .44 Magnum and very soft (almost pure lead) cast Lyman 429421 (Keith type bullet), in the early '70's. I discovered that the bullets were loosing their shape at moderate velocities and rifling marks were observed on the nose of the recovered bullets where no rifling marks should have been...there were beginning to look like wad-cutters as the velocity increase, bringing about concerns about possible high pressure.
If ya can scratch it with ya thumbnail it`s close to pure Pb 5-7 bhn
If ya can`t scratch it but can dent it with ya thumbnail it probably has some tin 8-11 bhn
If ya gotta work hard to dent it even on an edge with the thumbnail it probably has tin/antimony mix but not hi %s 11-15 or so
If it`s hard as woodpecker lips & ya broke ya thumbnail it has a hi content of tin/antimony 15-22 bhn & should be mixed 50/50 with pure , as the hardest of alloys is not needed for most handgun applications.
For 357/44 mag I shoot for 12 bhn with a bit over 3% tin to tuffen the bullet a bit so it does`nt shatter & it grabs the riflin better.
Of course this all depends how hard ya thumbnail is & if ya bite em or not
If ya care to send me a peice I`d be more than happy to test it with my Lee bhn tester though .
Wanted to add: I`d bet what you have is pure if it`s in sheet or slab form & I`ve seen muzzle loaders trade 2# for 1# pure to cast for the smoke poles !
If ya can`t scratch it but can dent it with ya thumbnail it probably has some tin 8-11 bhn
If ya gotta work hard to dent it even on an edge with the thumbnail it probably has tin/antimony mix but not hi %s 11-15 or so
If it`s hard as woodpecker lips & ya broke ya thumbnail it has a hi content of tin/antimony 15-22 bhn & should be mixed 50/50 with pure , as the hardest of alloys is not needed for most handgun applications.
For 357/44 mag I shoot for 12 bhn with a bit over 3% tin to tuffen the bullet a bit so it does`nt shatter & it grabs the riflin better.
Of course this all depends how hard ya thumbnail is & if ya bite em or not
If ya care to send me a peice I`d be more than happy to test it with my Lee bhn tester though .
Wanted to add: I`d bet what you have is pure if it`s in sheet or slab form & I`ve seen muzzle loaders trade 2# for 1# pure to cast for the smoke poles !
I've got some 30 lb lead bricks, too. I was told they were salvaged from a nuclear lab that was decommissioned (no, they don't glow in the dark). If that's what yours are, too, they are pure lead and unless you want to cast ball for cap and ball or musket, you'll want to add tin and antimony to bring the hardness up a bit.
A common strategy is to add Linotype metal to pure lead, but how much depends how hard you want it to be. 2:1 is a good general purpose mix. Modern lead-free plumbing solder is usually 95% tin any more, and will serve as a close-enough your tin source. Elmer Keith used 16:1 lead:tin casting the bullets he developed the .44 magnum with, so you can actually use tin alone. It just costs more.
A common strategy is to add Linotype metal to pure lead, but how much depends how hard you want it to be. 2:1 is a good general purpose mix. Modern lead-free plumbing solder is usually 95% tin any more, and will serve as a close-enough your tin source. Elmer Keith used 16:1 lead:tin casting the bullets he developed the .44 magnum with, so you can actually use tin alone. It just costs more.
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WOW... I bet these are the same thing. The machine these came from was used for measuring radioactivity. And YES. I had them analyzed in the replacement unit before I handled them. All was found to be A OK. I was thinking they would be on the softer side... I think Ill go with the solder method. At 16:1 Ill use 8lbs lead and 1/2lb solder correct? The first rounds will be for 38spec.
dagger dog
New member
I have the Lee hardness tester, after some time learning the how to use it, I have found most clip on type wheel weights will test out at 13-13.5 Brinell.
Using the chart that came with the test unit it puts the pressure range for 12-13.4 Brinell roughly between 16000-17000 psi , Well within the range of most 38 Special loads, with a good lube and water quenching you might push them into the +P range.
9MM Luger loading pressures run into 30000 PSI and higher and could cause leading problems with straight clip on wheel weight bullets, adding tin,
lino type or heat treating can make them quite harder.
Using the chart that came with the test unit it puts the pressure range for 12-13.4 Brinell roughly between 16000-17000 psi , Well within the range of most 38 Special loads, with a good lube and water quenching you might push them into the +P range.
9MM Luger loading pressures run into 30000 PSI and higher and could cause leading problems with straight clip on wheel weight bullets, adding tin,
lino type or heat treating can make them quite harder.
Thats good info. Thanks Dagger Dog. I plan on doing my first casting session this week. Wasnt sure if I was going to quench or not but I think I will now. And Ill plan on adding some lino or tin to the pure lead I have to come up with some good 9mm boolits. Now, to figure out a mix for that.... 