I shot my new 6br yesterday, the previous afternoon I shot 10 bullets to brake-in and velocity test. So I made 2 generic loads seating die depth didn't change for the 2 bullets used. 31 grains of varget topped with a 107 SMK shot a 5 shot 1.5" group at 600 yards. The same Load with the 107 Matrix went into 4 inches. I will give them another go and try and tune a seating depth. Velocity of both bullets averaged 2850.