Craxon,
Simply pushing a ball or plug down the bore to remove a dent will not completely remove it. This is because steels have elastic properties. Depending on a number of things such as alloy, heat treat, cold forming, etc., the elastic region (also identified by "yield point") can be high or low. But all steels have elastic regions. That means that it won't act like clay and simply hold a shape that it is deflected to. It must be "over deflected" or "over bent" since it will spring back a certain amount depending on where its yield point is. This is why the hammering along with a plug is necessary. The hammering cold forges the steel while the plug is in place.
If you are not comfortable working with steel or this is a valuable gun, I think you'd be better off sending it to Mike Orlen, Steve Bertrum, or one of our other gunsmiths.
