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Old March 9, 2011, 10:44 AM   #12
Join Date: March 4, 2005
Location: Ohio
Posts: 11,547

My advice was going to be to run a test on some pure lead to calibrate against, but thought I'd better try it first, since Lee's published scale for the tool stops at BHN*8. Well, the resulting indentation (Hornady pure lead ball filed in half) was too big for the scale on the microscope. The problem is that it was too big by too much. I ran the Brinnel formula for the 5/32" ball bearing used in the Lee tool and their 60 lbs force and got exactly the numbers on their chart. The problem is that should only have gone to 0.105 for pure lead and the dent I got was probably 0.010" bigger than that.

So, I'm going to have to figure that out. It may have something to do with it being swaged rather than cast, but I need to prove that. It's the opposite of the too-hard numbers I was getting before. I've got some pure lead brick surplussed out from the dismantling of a university nuclear lab. I've also got some instruments to let me calibrate the force applied by the plunger and I'll let you know how that comes out. When I get it solved, I'll be able to give you a more sound recommendation.

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