Mike,
As I've pointed out before, 7x57's vary considerably in how much powder they'll take, due to variations in throat length. Mine custom rifle was chambered with a PT&G "target" reamer with a short throat, so doesn't need as much powder to get the same velocities as most other 7x57's. I've only tried 4451 with bullets in the 160-grain range, mostly because they all shoot to the same POI in this rifle, and 45.5 grains of 4451 gets right around 2700 fps with most bullets, from a 21-inch barrel.
