I have been loading the 257 Wby Mag for several years now, and have found that it likes Nosler BT 115 with 69 grs. R-22. I have tried H-1000, and IMR-7828 and IMR 4350 and found that R-22 shoots the best in my rifle.
The 257 shoots straight as a string out to 350 yds, and with the R-22 load...
I have loaded the 180 Bt in my 338 and it shoots great. A ragged hole at 100yds and under 2 inches at 300 yds. I use the nosler manuals max load for IMR 4350. Nosler really has good bullets. I have never shot any of their bullets that did not perform great.
It gives instant kills on Texas...