H-1000, Weatherby brass, 215 primers, w/115 Baltips 3.305 OAL, start at 72 grains and work-up MY rifle shoot 76gns., Yours may be completely differant!! better safe than sorry!!. My rifle has been rebedded along with the pressure point. (needed!) I have found factory barreled Weatherby's don't shoot as well until over 100+ rounds have been fired! Then they came in shooting well under 1" at 200, these are my 2 .257's. You must let the barrel cool completely between groups and shoot no more that 3 shot groups. Keep the barrel clean!! I had alot of fouling in those first 100 rounds! I clean after 15 rounds the most.
I also have used the load in the Speer book with IMR 4831 and their 120 grain spbt, this was also a good shooting load in my Lghtwght. It's a fantastic cartridge! Good luck!