If your looking to wring out the last bit of accuracy - try weighing your charges.
Before anyone says it can't be done, I did it for years. I don't shoot T7 or Pyrodex any more, but it sure helped my groups by weighing the powder. There is no other way to get your charges to within a tenth of a grain.
I was a fanatic for a while over accuracy a few years back. I took a Rem 700 mz and had it bedded, recrowned, and a shilen trigger put on it. I used Precision rifle bullets and T7 powder. I weighed powder and sorted sabots and bullets by weight.
All of that stuff helps if you're after tiny groups.