Note that the human element is always in the equasion as long as the rifle is touching the human. Benchresters eliminate 99% of the equasion by shooting their tack drivers in free recoil as the rest atop bags on a bench and the only human thing touching them is their trigger finger tip on the rifle's 2 ounce trigger. That rifle so held recoils exactly the same way while the bullet's going down the barrel for every shot fired.
Holding a rifle to ones shoulder with its stock resting on a front and somethimes a rear rest typically shoots less accurate than if clamped in a machine rest fired in total free recoil. Us humans don't hold a rifle with the exact same pressure and force angles and position for every shot. After watching several folks at a rifle range shoot the same scoped match rifle and ammo producing 5-shot groups from 3/4 to over 2 inches at 100 yards, I learned a lot. That rifle and ammo would shoot under 1/3 inch all day long from a machine rest.
US Navy Distinguished Marksman Badge 153
Former USA Palma Team Member
NRA High Power Long Range High Master
NRA Smallbore Prone Master