Sunday, April 10, 2011

Annealing Lead Alloy for Softer Boolits - First Results

For background on this test, please read the prior post.

The cast bullets used in this test were annealed for 30 minutes at 450 degrees.  The oven was turned off, with the bullets inside, until cooled.

Here is the data in chart format, click on the chart to see it full size:

This particular air cooled wheel weight alloy tested as 10.4 BHN, the day after casting.  A bit hard, but in the range of modern day wheel weights.  After six weeks and just prior to annealing they tested at 14.2.  Immediately after cooling they dropped to 8.2.  That's a pretty big drop in hardness.  After 7 days they age harden back to the 10.4 as-cast hardness.

I plan to test them again next week to verify just how they continue to harden.

It's a nice surprise that the hardness dropped to 8.2, just what I had hoped for.  As you can tell, they don't stay there long.  If you cast & load with a just in time approach, this can be very helpful.  If you cast thousands of bullets to be loaded over the next year, you can still anneal in smaller batches, as needed.

It's encouraging to know that the wheel weights can be softened.  The consistency and accuracy achieved in a 357 Magnum with softer lead is measurable and noticeable. 

I plan to roll this new-found-knowledge into my current casting-handloading-shooting schedule.  Currently I cast 5-10 lbs of a given bullet, let them age for 2 weeks, lube & size them.  At that point they are ready to load then shoot.  Usually lasting for 2-4 weeks.  That's with 2 different bullet designs going, shooting 200-250 total rounds a week it works.  Now I'll anneal-lube-size a week in advance for bullets that need to be a softened up.

Hope this helps and gets you to 1 ragged hole at 25 yards.

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