On the bull moose I shot at 300 yds, I recovered the 220 grain sierra gameking boattail bullet out of his spine. It was perfectly mushroomed and retained a very high percentage of its initial mass. I've communicated with Sierra about this bullet and the jacket is thicker than on some of the smaller gameking bullets. It was built for launch out of 8mm magnum velocity cartridges at cxp3 game. The other critters I shot with this bullet, I can't comment about weight retention as they were complete pass throughs. But the wound channels and exit holes do give a clue about the performance of this bullet.
If you want some load data Noel, send me a PM and I can give you some indications of what works for me.
If you want some load data Noel, send me a PM and I can give you some indications of what works for me.