IIRC.. from my deer hunting days of 20 years past, my best was around 4 inch group at 75 yards (where I sight in) with the good 'ol challenger sluggers.. 20 inch smoothie with rifle sights (irons)
Now I run a rifled barrel and Hornaday SST.. and best ever was around 3 inch group at 100 yards with a scope. Based on the evidence and the distances I am prone to shoot at I think I may switch back..lol
Also the rifled barrel and SST is much more punishing to my shoulder and cheek. Sighting in was agonizing. .... and I barely blink when firing any 30/06 or 300 WM