When comparing similary weight for caliber bullets there isn't too much difference out to 500yrds. After 500yrds they start to separate in favor of the .264
Here's a comparison:
At 500yards
.257 115 grn berger bullet BC of .466 drop of -37" drift(10mph) 16.4" 1312 ft/lbs
.264 130 grn berger bullet BC of .552 drop of -41.4" drift(10mph)14.7" 1453 ft/lbs
At 1000yards
.257 drop -253.9" drift 80.3" 559.2 ft/lbs
.264 drop -262.00 drift 69.8" 709.2 ft/lbs
So the big difference is in wind drift. So for me I chose the .264 due to the much higher BC bullets you can get and the higher Sectional Density of those bullets.
Can't go wrong with either one.
