I have never experienced a problem with RE-22 powder. It is consistantly the most accurate powder in my 300 WM and my 280 AI. In fact I have shot under .25" groups with 168gr SMKs in my 280 AI and consistant .50" groups with my 300 using this powder.
As far as bullet selection goes I would think a 140 or 150 would be perfect for either game.