Robb, if I recall correctly years ago there was a gunsmith down South in (Florida or Texas?) who converted Pythons to .41 Magnum. Colt took him to court and don't know what happened after that so perhaps it is a leftover barrel. Some others do Python .41 Special conversions and it could be from that, too. Colt made a prototype .41 mag from what I read but it never got produced and was put in the vault or destroyed. Reeder makes 5 shot .41 mag GP100 Conversions using his 5 shot cylinder and Clements 6 shot .41 Special conversions (he claims 1250 fps 220 gr loads) using the stock cylinder. Reeder uses his own barrel and Clements a rebored GP100 barrel. Perhaps, if you run into Grant Cunningham down the road a couple miles in Falls City he could tell you more being he is a noted revolver guru.