Boolits from zinc/pure lead 50/50 alloy; interesting results.

[lathesmith]

sagacious, I was wondering how much zinc it takes to be destructive to our casting pots. Is the amount necessary to be destructive greater that the 1.7% soluble threshold, or lower?
lathesmith

[Traffer]

I know this is an old thread. But I have found it relevant for what I am now doing.
As many of you know I have been developing a workable 22 rim fire reloading system for the past 3 years. I want to deal with a situation I had the other day. I discovered after fighting to mold some 40gn, 22lr bullets, that I had zinc in my batch of lead. I had been using very soft 6bhn lead and decided to add some harder stuff to the melt to get some harder bullets. Unfortunately it looks like I grabbed some zinc contaminated lead. Since I swage the bullets after I mold them, it is not critical that they be perfectly molded bullets. So I soldiered on with the molding of some 200 bullets. I found out after the fact that there was zinc contamination by putting a few drops of muriatic acid on the left over batch. Fizzing and foaming...sure sign of zinc. What percentage? I have no idea. The bullets were harder but it was very difficult to get a good idea of the hardness with the pencil hardness test that I do. My guess is that they are about 10bhn. They swaged up well (though a bit more pressure needed). I did a crimp test by measuring the amount of bullet pull in lbs to pull out of the crimp, I noticed something that seemed weird to me. The bullet pulled at about 78lbs of pull. (That crimp would have been about 30lbs with the soft lead). But the bullet pulled like taffy before letting go. It stretched to about twice the original length of bullet. (sorry no pictures as of now...I will try to get some). I am very pleased with what I have learned here. Lead-zinc alloy bullets may be something that will work out very well when they are swaged after molding. There are a lot of benefits that may be gained by Pb/Zn alloy.

[Wayne Smith]

Not if an uncrimped boolit pulls out of the case at 78lbs! Talk about high pressure excursions!

[therealhitman]

But the bullet pulled like taffy before letting go. It stretched to about twice the original length of bullet.

[Traffer]

You will note that it WAS a crimped bullet. It was a deeply crimped bullet. I have tested some factory ammo... Remington Golden Bullets pull at about 25 to 30 lbs. And Winchester Super X pull at about 60 to 68lbs. My goal has been to make the crimps hold between 45 and 55lbs. I was not able to attain that with soft 6bhn lead. The highest pull rate I was able to get was about 35lbs, no matter how deeply I crimped them. That is why I went to a harder alloy. Again, the same crimp that held around 30lbs on soft lead held over 75lbs with the Zinc/lead that seems to be about 10bhn. In my research I have found that 22 rim fire loaded with modern smokeless powder needs a heavy crimp to provide the necessary confinement to get the powder to burn under compression. I am not 100% sure why center fire ammo does not require the same conditions. Perhaps because of the fact that there is a lot more powder in a center fire or because center fire cartridges provide the confinement to pressurize the burn by fitting in the gun tighter. Or maybe a combination of both. But in the book "Ammunition Making" by Frost, he is very clear pointing out the need to have the crimps consistently hold from 45 to 55lbs for match grade 22 rim fire ammo.

Not if an uncrimped boolit pulls out of the case at 78lbs! Talk about high pressure excursions!

[Traffer]

I take it this is a shot at my eureka moment. If so, Yes it felt just like that. It was like "wow I can now do things that no one else has ever done...maybe"

[therealhitman]

Yes, definitely a eureka moment I would think. Lighter weight, added lubricity plus elasticized alloy potential? Does that all lead to lower powder charges for like velocities plus less mechanical wear combining to minimize erosion? Or am I excited over nothing? (wouldn't be the first time)