The most extreme example I've seen with factory vs. bedded was with a buddy's Rem. 700 in .222 Remington. A light recoiling caliber, yes. He had a 3X9 scope on it and shot Remington factory 50 grain soft points in it most of the time.
As you worked the magazine empty the group got larger as the point of impact, even at 100 yds., worked up and to the right. After 5 rounds you'd have a group the size of the palm of your hand.
We removed the bump in the barrel channel, removed wood from the area of the stock where the receiver made contact (from front to back) and about 3 inches in front of the front trigger guard bolt.
We used Brownell's acraglass. Followed the instructions and had some of the materials left over.
A day later we took it out of the vice, popped it out of the stock, cleaned all the release compound off of it, wiped it down with an oily rag and put it back in the stock.
We took it down on an old farm near the river and measured out 100 yds. and he shot 5 shots. I don't remember the groups size at 100 yds. I do remember that when we added another 50 yds. to it (one side of the field to the other) he shot another 5 shot group. That one was covered by a dime.
Palm (of your hand) sized 5 shot groups at 100 yds. to dime sized 5 shot groups at 150 yds. He was "extremely" happy with his old rifle after that.
On another note, in three years of ground hog hunting I never saw him kill a ground hog. Why? It doesn't matter how tight a group you can shoot with your rifle if you keep thinking the ground hog is 200 yds. away instead of 125 and you shoot over their heads every time.
There's a reason why the big rifle teams have their rifles bedded.
