Partsman,
That is one of the added features to the heavy barrel.
A short thick barrel has less flex in it and will distort less when fired.
All barrels flex a little when shot, even cold. A thin ling barrel will flex and launch the bullet a micro fraction of an inch up, down, side to side or diagonal and the rate at how much it moves and if it moves in the same direction every time will effect your 100 yard accuracy. The bullet is not in the barrel for a long time. On a M700 it takes longer for the firing pin to move from the trigger release point to the primer than it does for the Primer to fire, ignite the powder charge, expand the crimp and for the bullet to reach 2000 Feet per second and leave the barrel and trigger pull has more effect on accuracy than most other factors and the heavier rifle will tend to stay in the same position and not have over travel move the barrel. one degree does not sound like a lot of movement untill you extend it out over space and what looks like the same line in 3 inches grows to 3 inches over 150 yards.
The longer the barrel the more the flex and the more the bullet will move. Enough to tell between a model 7 with a light 20" barrel and an SPS with a heavy 20" at 100 yards with all things being equal. Probably not. Will both work. Yep!