Bullet testing media can yield excellent indicators of bullet performance, but it's difficult to replicate the complex mosaic of hard bone, solid muscle, and soft tissue a bullet encounters in game.
But like the Christian Soldiers that they were, they quickly reminded themselves of words of Hafiz that said: 'In the time of trouble, avert not thy face from hope, for the soft marrow abideth in the hard bone.' So they went on cracking the bone in order to get to the marrow.
Osteotomy in hard bone requires high-speed drilling under a copious cooling system, in which case minimally irrigated low-speed drilling is out of the question.