Here is a novel slug idea, hard plastic support ring on the front, and a locked base ring/seal. Metal never touches the bores. Work in great rifled and good in smooth barrels. These are steel, lead/copper would do great also.Could be made heavier and different points. Flat point shown would do great damage to game. On the net- ammunitiontogo.com This one is about 500 gr.
Second picture is the 499HE to use in redoing the 500S&W, shown on the also, in single shots, etc,for those wanting much more power at 40-50% lower pressures.Ed