Curious to hear about your most accurate big bore setup. How tight are the groups and what efforts, adjustments, and testing were required to get there? Any tips or tricks for improving accuracy? Any tips for what NOT to do?
Simply shooting the rifle will get you to a point that you know the quarks of it. Some like a firm hold, some like to simply be settled on a bag or the hand. Barrels are individuals and some like a good polishing and kept clean. Whereas other's like to be kept leaded in and never need a cleaning. (The latter is usually afters good polishing and shooting lubed pellets or slugs.)
My most accurate is an American Air Arms 357 Slayer bullpup, shooting swaged slugs. It can shoot MOA groups out past 200 yards if I do my part. First six shot group, cold bore out of the case at 100 yards.