I have a Tikka TT3 Tactical in 308 call and As stated by the factory I did not do the breaking procedure indicated by some shooters. I am shooting sub 1″ groups at 100 yards. I am not trying different hand loads to find out my vertical stringing for the harmonics. I have shot 15 shot .6 groups with my hand loads I have over 600 rods through her now. Good luck, I got a beautiful shooting rifle from Tikka