Weights are def not the answer, if your gun is stock heavy, remove some wood from the stock, take the pad off and drill a hole.
this is a trial and error method, but it will give you a spot on balance, it may take a couple of removal sessions,
If you over do it, get some lead, or fishing weights and tape to back of stock until correct balance is acheived, then in a peice of scrap wood drill a hole using the same bit, you used on your stock, then melt in the lead and leave to cool. You now have an exact sized bung for the stock, place it in the hole and refit pad and check balance, you may need to move it back or forward in the hole, once done bond it in
If you take your time, in the removal stage, an exact balance can be achieved, I have just got a Franchi which someone has balanced and over bored, so they have used dowel to make up the weight, as white wood in general, is lighter than walnut.