Lead hardness for lapping

[abishai]

I seem to be having trouble getting my bullets the right hardness for lapping.
I had a batch of bullets, cast from straight WW.  The .311" 150g were at 12BHN and the .357" 158g were at 13BHN -both of which are fine.
However, my .433" 320g were sitting right at 14-1/2BHN - a little too  hard.
These were all cast from the same batch of lead.
O I placed the .433 bullets in the oven at 350F for 1 hour, then let them cool slowly.  They started out at 7 BHN, and over the last 3 weeks have climbed back up to only 10-1/2 BHN.
I'm measuring using the LBT hardness tester.
Shouldn't they reach the same BHN they were before within 2 weeks, and at least 12 BHN anyway?

Jeff

[Veral]

Hardness for lapping isn't so critical that 1 bhn makes a difference.  Problems with too much hardness starts at 16 bhn in my experiance, the problem being that bullets spring and follow increasing bore diameter, which increases diameter where we don't want too.  When too soft, it requires too many shots and works the throat too much.  A few soft bullets after a bore is straight will put a finer finish on and save some of the elbow grease required to polish.

Bullet hardness is very much related to cooling rate after the cast.  Therefore, annealed bullets will never reach the hardness of air cooled.