The ball diamter and the force used are the defining elements of the Brinell test.
Were the (current) LEE tester to not to dead nuts duplicate certified Lyman#2 as
BHN 15 (over many samples/over many years), I'd not be drundling around trying
to figure out why it's very consistently reading 5.7-6.0 for what is certified 30-1.
("supposedly" to BHN 9)
And were I not also able to read the sample indent diameters very precisely/repeatably
using both scanner and microscope, I'd also not be scratching around trying for explanation.
But right now ... `tis a puzzlement.