enough to affect POI, especially at distance (past 30 yds). Even with the top brands, there are tins shipped with 2 sigma varance of 0.02 mm or more from nominal. There are also shifts of 0.02 mm or more in the nominal, and this would also give results as you describe. Cliff Tharp was one of the early adopters of the Pelletgage, and he wrote about his pellet selection and experience on several of his "Varmintair" BLOG posts. Cliff has retired the BLOG, but this link will take you there. I understand Cliff is still doing well, and shooting, but spends less time at the computer these days.
It may be useful to be certain your pellets are consistent, and that they are the best size for your rifled barrel.