Took my 257 Wby out today loaded with N570 at 77.0 grains. The load was way faster then I had hoped and shot just under .750. It chrono'd at 3574 fps with an ES of 2 and SD of 1. All of this tested with a friends Lab Radar I was blown away with the results. My old load was 100gr TSX at 3602. So this load is knocking right on the door of that. Just need to sight in and wait to teach a deer a lesson now.