I had one of these and what I did was cut a thin strip of maple 1/16 wide ,maybe a foot long, soaked it in water to make it pliable , then put some elmers glue on it and lay it into one side of the 3/8 ramrod groove. I pressed an 5/16 rod into the groove, thus forming the thin strip into the side of the groove, effectively building up the side that the groove had drifted off too. I was then able to widen the other side a bit effectively moving the groove over a bit. The hole on inside was widened a bit and then I tapered the rod towards the breech. End result after finishing is that it is almost invisible. No body would know but me. This occurred because my blank stock wasnt square top to bottom, and I didnt make sure it was right. Live and learn.