Tell you what my first high powered rifle was a remington 30.06 BDL, I neglected it as a 15 year old. It shot the best groups of any gun I have owned. I'm so sorry I sold it when I was enlisted Navy. I have a 300 Win Mag that I'm breaking in to this day, 60 rounds and when it stops fouling to the point I deem good I will work a load. A 308 I have has shot 1/4 groups since the 10th round. I depends on the gun and the roughness of the rifling, and I suspect the length of the barrel. When you deem it's broke in, it is.