Hunter,
6.5 Rem Mag case capacity is very similar to 6.5-06. Starting loads for the 6.5-06 should be safe as would 6.5-284 loads. I had a 6.5-06 at one time and I could fill the case to the neck with H4831 for 125 NP. I never experienced any signs of excess pressure and it was a deer slayer. I...