I picked up a 4 inch 10mm Smith & Wesson revolver barrel thinking I would swap out my M610 6 inch barrel with a 4 inch barrel. After purchase, I looked at the bore and said to myself looks rather large(should have paid a little closer attention. I literally did not think to check the bore diameter before purchasing). A 40/10mm bullet drops thru the bore with room to spare as does a .44 mag bullet. The throat of the barrel measures .440 and the muzzle measures .443. I look forward to feedback from the vast knowledge of forum members. The rifling looks very sharp and appears to haver never passed a bullet.
It may have been fired, but the bullet didn't touch the barrel.
All kidding aside, is there some way you can return it? I had the same problem with a SAA barrel which was marked .45 Colt, but was actually bored for .44 Special. I didn't catch it, but when I shot it, boy, did that thing KICK!!
I bought the barrel from a very reputable firearms vendor. He has offered to take it back and give me credit for future work or purchase. I just wanted to throw this out there and look for comments. The bore diameter is puzzling as I have not found a cartridge utilizing the bore demensions. Maybe someones attempt to create a wildcat cartridge, and gave up.
It looks like it has proper S&W roll markings but I don't see how S&W could've "accidentally" made this. Making one of a kind is easier said than done. Perhaps the original owner had it re-bored for some kind of special project, then decided not to use it or died or whatever, and then it was passed off as an ordinary 10mm barrel? Is there any way you can find out who the previous owner is?