old ropers link to Lilja's barrels used for records is something to think about. The 600-yard aggregate for group shooting are the average of several groups shot. The largest groups are typically half again as big as the average. Agg's in the 1.7 to almost 2 inch range happen when the largest single goups about 3 inches.
While to some this may seem exciting, but such groups from free recoiling rifles virtually untouched by humans today are no smaller than test groups with rifles normally fired from the shoulder shot around 1970. Which to me means, all the modern stuff ain't any more accurate than what some Winchester 70 based rifles did 40 some odd years ago. With full length sized cases to boot.
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master