New England Arms 243 cal single shot

I have one of these when I take it to the range to shoot the first shot is right on then the next is off a little then the 3rd is off even more. Somewhere I read that if you would sand out the forearm so it only touchs at the screw mount that this could help this problem. Has anyone had this problem or read anything like this.
Any advise would be greatly accepted THANKS!!!! Or tried this