Hey FG,
At one time I was playing with the idea of filling the hollow point of a PB with lead and making a flat meplat out of it. It would be similar to the 444 PB but made out of any of the PB's. I got busy with other things and never got back to it so never got to test any of them. I'm sure your steel core idea holds up better than a lead one but is a steel core bullet legal in CO? I may try to make up some of myversion of PB and see how they shoot. I have some wheel weights that might help toughen them up a bit more than pure lead so that might be the way to go. If I get a chance to make some up maybe Ican send some to you to test in your sand box for comparison.