After listening to some comments by Erik Cortina I think a 7x6.5 PRC could be interesting.
F Class John has been experimenting with his friend's design called the 7mm-3DP, which is also based on 6.5 PRC brass.
The 7mm Short PRC (McWhorter 7SPRC) caught my eye awhile back. Just neck up 6.5 PRC brass to 7mm. Choose from Lapua, ADG, or Peterson brass.
