I wouldn't do a thing until I shot it a bit. It might surprise you. Maybe I'm lucky, but the handful of #1's I've owned were spiffily accurate right out of the gate.
I’ve had the exact opposite experience on the four that I owned. That applied after all the so called accurizing actions. OP, in my view, if it shoots 1.25” groups out of the box, you got a good one. Great cartridge, the 257 wby.
