I realize I am coming into this discussion late, but I think my experience might be relative. At one time I wanted to open the fixed choke on my inexpensive single shot Savage 20 break open. So I called Brownells and tried to order a choke reamer. The salesman on the phone talked me out of it saying I could accomplish the same thing with a half inch dowel rod wrapped in wet or dry sandpaper. Took me a while and quite a few trial shots but I got it where I wanted it. Then my buddy, who has similar Savage told me his gun shoot the pattern to right of center, about 8 to 10 inches at 15 yards. Once again the dowel rod and sand paper were employed, only to the left side of the muzzle only. After a few trial and error sand-and-shoot sessions, we were able to move the left edge of the pattern.
Luckily for us both, those inexpensive guns do not have chrome lined bores.
Mergus
