Re: .264 win mag loads
I run a sendero chambered in 264 for a hunting rig. I follow barnes reloading manual for 120 TTSX's. There are a couple folks here that run match guns chambered in 264 as well. The 140 SMk's are a pretty popular bullet with eiter R-1000, Retumbo or 4831SC for powders. I would follow the std procedure of starting low and working up a load with slightly higher powder charges, watching for your node and of course pressure signs.
As stated, it is a caliber that can be a touch hard on barrels...but I sure love mine.