Lee Lead Hardness Testing Kit

[mt_sourdough]

The instructions with Lee's Lead Hardness testing kit says you need to test an area where the alloy was close to the mold. Hmmm.... I'm not a metallurgist so I am a little confused.
You see, I did some cross sectioning of some jacketed bullets and I wanted to test the alloy hardness of the cores. When I did, the numbers indicated a hardness that is softer than straight lead.
That is when I read about the need to test cast bullets at an area of the bullet that is close to the mold when it was cast.
Anybody have any insight for me?

[Ranch Dog]

I guess that means the skin, not the core.

[RBHarter]

Lead work softens cores are made from extruded lead wire then swagged inside the jacket although some of the bonded are poured they are then swagged to shape. The finished cores wind up being about dead soft. Your cutting means will also work the lead. The cores when poured for ingots will run 8-10 BHN and water drop or heat treat to 14 BHN adding pound of hard shot in 20# will bring it up to 18 BHN .

While I doubt that it explains it but maybe it sheds a little light .

[mt_sourdough]

Thanks for the responses. I remember a debate about this subject with guy at CastBulletAssociation and it seemed the argument went back and forth with some who claim they can prove that the bullet remains the same level of hardness throughout.
I have done something around (I'm guessing) a hundred terminal ballistics tests with cast bullets and all the evidence suggest a sort off crust layer and then softer lead on the inside. On water quenched bullets the difference is quite pronounced. Outside layer breaks away in chunks while the inner alloy smears.
That was my 2 cents in the debate, but these guys were far more pedigreed than my high school level credentials.
I guess with swagging, that adds a whole 'nuther perspective.

So, I guess my next question is, is there another type of lead hardness tester that could attain numbers from jacketed bullets or is that just a no-go?

[RBHarter]

Castboolits has had many discussions .

The short semi scientific answer is the rate of cooling influences the finished hardness so force cooled bullets will be harder deeper than air cooled. The hardening is caused by arsnic and antimony. The faster it is cooled the harder it forms structure.

[Fyodor]

You could make a quick test on how much all that effects lead hardness:

1. File a very small flat, just large enough for testing.
2. File deeper
3. Cut bullet in half and test in the very center
4. Hammer a small flat
5. Hammer deeper
6. Crush the bullet to a "coin"

And compare hardness. It might be interesting how much distance to mold surface (cooling quickness) and work actually effect hardness.

[daboone]

Personally I never found a significant difference between a filed surface and just pressing an appropriate surface of my cast or ingots. If I can get the BHN into the appropriate range that seems to make the cast perform the way I need/want. However it is necessary to wait at least a couple of weeks to get an accurate or consistent reading.

[Chajohnson]

I thought the Lee tester did not accurately measure anything below 8 BNH?

[daboone]

I thought the Lee tester did not accurately measure anything below 8 BNH?

The Lee tester will show indents greater than .079 (BHN #8) however you're correct the tables provided only show .079 and smaller.

[Chickenthief]

There is a better chart avaliable: