I asked Walt Kirst this same question, and yeah, the rebated cylinder means the back end of the cylinder is pretty small (it actually uses undersized charge chambers to get the thing to fit at all, even as a C&B. Think of the cylinder as a hybrid .31/.36) He told me if I was bound and determined to convert it, I could use a '49 conversion to .32, then either sleeve the barrel or use a '49 barrel.