I have a 8" twist 22/250 . Its my varmint rifle and have easily shot 1500 rounds thru it. Well I guess I shot the throat out. Today at 25 yds bullet holes were oblong and keyholing . Gunsmith who chambered it also says throat is shot out and thinks (before chamber casting) that there is hope. Says he thinks he can cut and inch of chamber end and re-chamber and it will be fine. Have any gunsmiths done this before ?