I have a 4 screw K-38/M-14 that has a very slightly ringed barrel. It is so slight that it can't be seen on the outside. I have laid a straight edge scale along both sides and there is no discernible bulge. It can barely be felt when a tight patch is pushed through, but it is there.
It does not seem to effect accuracy, since it shoots almost a well as my M14-5, which is probably the most accurate handgun I own.
My question is, should I just live with the ring or should I rebarrel? I can get a very good condition 6" barrel for a rather reasonable price and I have the ability to swap barrels. Even with the cost of the barrel I'm still way ahead of the going price of K38/M14s in similar overall condition, (sans the ring).