You've got to go back through the rifle and verify action screw tightness (take the action out of the stock to start with), barrel clearance from fore end, etc.

4" at 25 yards seems like something is extremely loose. You aren't shooting from a wiggly bipod are you?

At 25 yards, a rifle sitting on its side and shooting by itself would make one lousy hole. (25 yards is a lousy distance to verify anything, I personally think. 50 is better, really)