With a bullet going down the barrel and 50,000 pounds of pressure behind it, the barrel whips like "a whip..."
NRA did numerous articles on this many years ago. Bottom line then, stocks were all wood, upward pressure between forend and barrel helped to minimize... My gunsmith buddy told me that he would hook a 9 lb weigh (no reason given for the 9 lbs) on the forend while the glass dried, rifle assembled... Figured it gave about 9 lbs up pressure...
Classic case, Brits testing .303 loads had a heavier bullet at a lower velocity striking appro. 12 inches higher than the faster, lighter bullet, same distance. Military barrel was whipping and happened to be "up" when the bullet left the muzzle... !!!
This is a big reason for the "bull barrels." The heavier/stouter barrels don't whip as much... Don't heat as fast either. "more mass" as the physicist would say.
So your goal has to be consistency, so the bullet leaves the muzzle with the barrel at the same point each time. Consistency in load materials helps. Then there are the tuning tricks beyond the up pressure. Some of the old target single shots had the fore end on a separate attachment to the frame, so that it did not touch the barrel... LUCK