Back then I did test the hardness of the pellets - we had the equipment at work - and there was very little difference between Magnum lead, copper plated, and nickle plated; in fact the magnum lead was the hardest, but the nickel patterned tightest, then copper, then lead.
I had no way to test roundness but they all looked about equal in that department. Of course after the outstanding pattern results with downright ugly original Hevi-Shot one has to wonder if aerodynamics plays that big a role at all.
