300 WSM, norma brass, F210, russian or RWS primers
either H4350 or VV165 and Norma MRP if you can find it.
Would try some Sierra 168/175 SMKs that have been sorted for base to ogive and weight.
26-28" Broughton 5C rifling barrel in 11 twist. .340 Neck reamer, tighter than SAAMMI but no neck turn. Custom Gunsmithing (John Myer) one of the top recommended gunsmiths on www.6mmbr.com
website has the reamer and is a proven master 1000 Yard gunsmith and shooter.
Easy to load and will more than meet any accuracy expectations.
Barrel life should exceed 2000 rds, my gun had 2300 through it and took 9th at 1k BR Nationals.