For the 300 ultra I would definately try reloader 25 powder.My own 300ultramags shoot reloader 25 better than any other powder with imr7828 a close second.Several other people that I know also get the best results with r-25 in their 300ultramags.I have not used the triple shock bullet but I would not hesitate to use a 168gr bullet of premium construction.I do however step up to 180gr bullets for moose and elk when bullets of conventional construction are used.