If you aren't opposed to fireforming you can improve the 264 Win Mag. It will outperform the PRC but it won't hang with the 6.5 WWH. Mine is throated to seat 156 EOL at 3.550" instead of SAAMI @ 3.340".
You will not be disappointed with the 6.5 prc I built 2 different rifles Year before last . One prc is on a long action pre 64 mod 70 win and the other is on a Curtis Axiom short action built as a switch lug so I can interchange too the 300 wsm with no other changes I can also wildcat cat too the 25 prc with no other changes using the same bushing dies for the 6.5 prc . A friend built a 264 win mag at the same time and our velocities are about the same with 10 grs less powder for the 6.5 prc . It also seems I can control my extreme spread easier on load development . The 6.5 prc case is a very strong case and so far I have loaded 123 gr absolute hammers just shy of 3500 fps and 109 gr absolute hammers 3722 fps with no primer pockets lost . My throating is at .145 I think the standard throating is .188 and the earlier was .133 I would go with .145 . The best powders will be N165 N560 R26 H4831 Rl23 andH 1000 I hope this post helps good luck on your choice .
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