kf4ocy
I too did not sense that anybody was trying to discredit you, or your dad. All I read were responses by guys who were giving the best information they had about this type of gun. And having owned a couple of these myself, the first one in 1981 being a 30/30 20 gauge, and owning one now (without a shotgun barrel) I am interested in as much information as I can get about them.
The truth is there are so many possibilities with these rifles that nobody actually knows everything about them. The best information available (until your posting) was that there were no accessory barrels offered until the new company made them available. That is all it is... the best information available. And from what I read, that is all that was said.. it was believed that factory did not offer them. It is also possible (even likely) that your dad stumbled on a deal much like the one described by carbine man.
Bottom line however, no one knows for SURE how it unfolded. Whether it might have been a special deal by a gun shop, or something done unofficially by a factory smith, or... whatever! (Example: there is a fellow here who has a 22 Hornet bull barrel, that was never officially made by the factory, but he has one and has the photos to prove it... another story)
You have a gun and two barrels, that much is known. How it came to pass is actually unimportant, and you weren't asking questions about the operation of the gun itself, you only mentioned that you were having trouble sighting it in. If that is still a problem after tightening the screws, are you looking for assistance with that?
The one thing most folks here are pretty firm about is safety, and there have been some concerns and safety issues with using a centerfire rifle barrel on a shotgun frame, particularly the older ones. That is what I believe Quickdtoo's response to your posting was referring... having a rifle barrel on a shotgun frame that may not be suitable for it. If that is not of concern to you, then it is not.
I will be so bold as to suggest that if you truly are sorry about getting on here, it is quite simple to leave. On the other hand, there is no other place that I have found with such a huge pile of valuable information and support for these firearms and, rather than leave, I suggest you stay, participate in the group, and try to take things less personally. You will be welcomed and will receive honest and sincere support if you want it.
(*note: sometimes honest support, though valuable, can be challenging to receive.)

And like carbineman said, if you can, post some pics and markings please. They would not only be interesting for some of us, but might be helpful for you to get more info.
Cheers
Kerry