Soon to be a 6MM ack.
Have you thought about making it a 243 Ack?
You can get that Wonderful Lapua Brass for it,Plus there are many many proven loads for the 243!
I have owned both,the Brass in the 243 is a VG way to go!
Good Luck with your adventure,I have to admit,the Deer wont know the difference!
Tarheel