I agree with the Doc!
Just get a new barrel, do what you need to fit it and put it in, and go out and enjoy shooting it!
I made a long rifle many years ago, used a coned 36 cal barrel, and it wouldn't shoot worth and dang. In fact, wouldn't shoot decent groups no matter what I, or anyone else did. So I tucked it away in the closet and shot a different gun with excellent success. A couple years ago I came across the rifle again and thought about shooting it. But then I remembered all the frustration from years ago, and instead of retracing those steps, just ordered a new Rice barrel, put it in, and the rifle shoots like a dream now!
I don't know what the problem was with the original barrel, but strongly suspect it was the cone.
John