Troubleshooting a rifle is like troubleshooting a car. You start with the easy, simple things and progress to the more complicated fixes if the easy ones don't work. Check the guard screws on the rifle to be sure they aren't loose. If you have a scope, check to be sure the mount screws and ring screws are tight. Take a business card and slide it between the stock and barrel from the fore end back. You should be able to slide it freely until you get pretty close to the receiver. If it hangs up, the stock should be relieved by removing wood. Take a Q-tip and run it around the muzzle to see if it hangs up and strands of cotton come loose. That would indicate the muzzle needs to be recrowned. Make sure the bore is clean - deposits in the rifling, either powder residue or copper, can mess up accuracy. If everything is OK, check out the ammo next. Jack O'Connor, a noted gun writer, once bought an expensive varmint rifle that wouldn't shoot better than 2-3 inches at 100 yards with factory ammo. He worked up some handloads for the rifle and it then shot into a half inch. Some guns are picky. If none of this works, I'd give up and have a gunsmith check out the rifle.