I'm on the same quest as you but I'm going to try 22-250 with Seafire's bluedot loads and 35-45gr bullets first.
Reducing the speeds and keeping some midrange killing power gives me something to play with but an excuse to buy a new rifle is fun too.

Good Luck!

"Camping places fix themselves in your mind as if you had spent long periods of your life in them.
You will remember a curve of your wagon track in the grass of the plain like the features of a friend."
Isak Dinesen