I recently purchased a Christensen Arms Ridgeline in 300 wsm. Doing their recommended barrel break in of 50 rounds, I bought a 20 rnd box of 165 Norma Oryx, a 20 rnd box of Armscor 165 NAB, and I loaded 10 rnds for a pressure test for future load development. I followed their break in procedures, shooting two 3 round groups, then cleaning. With the first box of factory Norma Oryx I noticed pressure signs of sticky bolt and ejector marks. The next 20 Armscor rounds with Winchester brass had no issues. I loaded the 10 rounds for pressure test off the Hodgdon data center for Winchester staball 6.5 powder with new Norma brass, 180 gr Swift Scirocco .030 off lands using ogive measurement, CCI 250 Magnum large rifle primer. Hodgdon data uses the 180 scirocco and shows starting charge 61.5 gr (2,720 mv) and max charge 68.0 gr (3,019 mv). I loaded the following for the pressure test and immediately had stiff bolt (worse than the factory Oryx) and noticeable ejector marks and primer cratering on all loads:
1. 64.8 gr, 2975 mv
2. 65.2 gr 3012 mv
3. 65.2 gr 3029 mv
4. 66.1 gr 3039 mv
5. 66.5 gr 3069 mv
i stopped after the fifth round. Powder was measured on my Franklin Arsenal Intellidropper that I use for other loads and velocities were measured with magneto speed chrono. What could my issues/causes of factory Norma having pressure and loads more than 3 gr under max having pressure issues and high velocities?
1. 64.8 gr, 2975 mv
2. 65.2 gr 3012 mv
3. 65.2 gr 3029 mv
4. 66.1 gr 3039 mv
5. 66.5 gr 3069 mv
i stopped after the fifth round. Powder was measured on my Franklin Arsenal Intellidropper that I use for other loads and velocities were measured with magneto speed chrono. What could my issues/causes of factory Norma having pressure and loads more than 3 gr under max having pressure issues and high velocities?