I'd say for the 264WM the best bullet is the 160gr Woodleigh Weldcore, and it's not particularly close. Nothing else can match the sectional density/penetration while still maintaining a decent BC.
Load:
--------
160gr Weldcore
64.8gr Retumbo
Nosler brass
Federal 215 primer
Lee FCD crimp slightly over 1/4 turn
0.02" to lands
Velocity averages 2910 out of a 24" Winchester.
Accuracy is plenty good.
"Nothing else can match the sectional density/penetration while still maintaining a decent BC." ?????
The .264" 160g WWC has an S.D. of .328 and a claimed B.C. of .509. While these are good numbers, B.C. and S.D. alone aren't the only things that determine penetration. Bullet construction comes into play, as does velocity at impact. Another factor to consider is that "more than an handful is wasted". Once a bullet exits there is no such thing as "more penetration".
A relatively standard 1-9 twist rate will provide marginal stability for the 160g WWC at 2850fps.
I'm willing to bet that a 120g TTSX or 130g LRX or SCII or 140g Partition or North Fork will penetrate as deeply out past normal shooting ranges. I put a .284" 140g North Fork (lower SD. and B.C.) through an elk at 400 yards with massive blood loss out the off side. Probably true for a variety of other bullets as well.
