Effect of Copper in Lead?

[BenW]

I've been playing around with the lead alloy calculator spreadsheet, but it doesn't seem to account for copper in the hardness calcs. My questions are:

1. How much does copper harden lead (% vs BHN)?
2. What percentage of copper is required to notice a change in properties?
3. Do you think there is a benefit to using it for handgun hollowpoints (10mm, 357 mag, etc)?

I may try copper alloys in handgun boolits anyways, but I'd like to know what to expect when tinkering: should I start with 0.5%, 2%, etc?

Thanks,
-Ben

[62chevy]

http://castboolits.gunloads.com/show...s-this-further

This thread answer a lot of your questions. I think you are wasting your time on pistol boolits unless you are thinking of hunting bear with a 44 mag.

[Hamish]

With copper, think "toughness", not "hardness". One quarter of one percent is in the sweet spot,,,,,,,

[scottfire1957]

http://castboolits.gunloads.com/show...enriched-alloy

I found that using the search function. There's more!

[rockrat]

I run somewhere around .18% in a WW blend for my pistols. Overkill, maybe, but sometimes I use the same alloy for rifle boolits <2200fps

[BenW]

With copper, think "toughness", not "hardness". One quarter of one percent is in the sweet spot,,,,,,,

So there's no appreciable increase in hardness with copper? Sounds like it performs a similar function as tin, not so much hardness as toughness.

I read all of the copper-lead alloy threads, but did not find specifics on what copper does to BHN, nor what is required to notice an effect. I saw that ~3% was max, but I wanted a little more info on what the minimum was to get an effect.

The problem I'm trying to solve, is I have a 0.401" 170 grain hollowpoint that requires extra tin to keep from fracturing. I'd like to reduce the amount of tin required with something cheaper. I can get the hardness required with antimony, but it adds brittleness. Yes, I can get there by playing around with tin and velocity, but I don't have a lot of tin. I also am trying to work up some loads for a 10mm, and I have to harden up the boolits even more than for my S&W (groups are opening up). I can either add more antimony (too brittle even at 40SW speeds) or tin (I'd have to go closer to 16-1, as I'm playing with 25-1 and 20-1). If I can use copper to harden the boolit without increasing brittleness, I'd call it a success.

I run somewhere around .18% in a WW blend for my pistols. Overkill, maybe, but sometimes I use the same alloy for rifle boolits <2200fps

Thanks Rockrat,

While I love reinventing the wheel (unrepentant engineer), my friend wants his 10mm back fairly soon (couple of weeks), and I don't have time to try every possible copper alloy. Having a range to play with helps me narrow down the amount of experimentation required. Have you experienced any trouble with copper buildup in a bottom-pour pot with that % of copper?

Thanks,
-Ben

[bangerjim]

The alloy I use to sweeten has 2% Cu in it. Add a bit of "toughness" to my bad boys.

[rockrat]

Nope, but I did run my pot about 15 degrees hotter. When I tried about 0.3% Cu, I did find my bottom pour spout would freeze up if I even too a half-minute too long to start pouring again, unless I ran the pot about 50 degrees hotter, but that put me at about 765 degrees. I went to the less amount of Cu and dropped the temp to about 710-715 and things are working fine.