needsmostuff made a statement that while I had thought of it,, and figured most realized,, is a the rebluing of the gun. Once you take a gun, remove a barrel, and add a new barrel,, it's very likely to need a rebluing.
I've been giving thoughts about this whole subject.
30 years ago,, Bill Ruger was still running things. The products were top notch,, and few had issues. Production was also a lot lower due to all this.
Current Ruger customer service still holds the "unwritten warranty" as the model of how they operate. But I'm reminded of a comment Bill once said. When someone asked something about collecting Ruger guns,, he replied with something like; "Hell no,, my guns aren't collectable. Buy them wear them out & buy another one!" And yet,, Bill was a serious firearm collector.
With the current business model,, another thing is the simple fact that while you can claim the gun wasn't abused,, the folks at Ruger have zero proof of that. I have enjoyed several conversations with the senior VP who ran the legal dept until just a few months ago. Long before this issue popped up,, we discussed things,, from a Ruger legal standpoint on servicing older guns etc. He said that if a customer claimed something,, without any proof,, in a court of law,, it would be considered "hearsay." Ruger prides itself in building a strong firearm. Yet,, once out of their hands,, they have zero control of how it was used.
Sadly,, there are several companies that have built very strong loads of ammo that can exceed the capabilities of many firearms,, that people put in guns not made for such ammo. And even the "hell for stout" (Bills comment once,) Rugers can have issues over long term use.
So the current warranty issues also have to consider all the possibilities and the facts.
I had a Redhawk that I bought in 1985. A few years later,, the barrel separated from the frame. It was the first of just a few of them that had that happen. The reason "Why?" was a big mystery for about 4 years. During that time,, Ruger THOUGHT it was a frame to barrel strength issue. They quickly designed & introduced the Super Redhawk in an attempt to fix the potential issue.
Turns out,, it was not the frame/barrel junction problem. It was an assembly method combined with the type of lube used.
Then there was the issue of the .357 Maximum "Top strap, flame cutting" that caused Bill to stop production & scrap about 5000 good guns. Yet,, in that case,, it was reloaders who were building ammo using hotter, faster powders, and very light bullets to give high velocities in that gun. Throw in a bad review by a snubbed gun writer,, (who didn't get a gun to review before others got guns,) and it killed the Maxi.
My point to all this long-winded post is that when Bill ran things,, if there had been a bad batch of barrel steel,, it would have had the issue arise,, been documented, and addressed because of proof of more than one bad forcing cone being revealed by the returns. Part of why I bring this up,, is 30 years ago,, silhouette shooting was popular,, and the Ruger Super Blackhawk was one of the kings in the game. If the forcing cones or steel was bad back then,, it would have appeared by those who shot silhouette a lot.
AND due to the current legal thoughts by Ruger,,, combined by lack of other barrels of that vintage having issues,, they have zero proof of how it was treated & the ammo used.
So,, yes,, it's very likely they looked at it,, figuring they have no info (other than your word) that it wasn't abused,, and figured it had been subjected to very hot or over loaded ammo in it's past.
One thing you as the OP hasn't mentioned,,, but by re-reading your original post,, I got the impression you are not the first owner. If I'm mistaken, my apologies. But if you are not the original owner,, and especially if you are the 3rd or 4th owner,, your knowledge of how it was treated prior to your ownership may be a consideration by Ruger. If you are the original owner,, again, my apologies. I'm just thinking of all the potential things that might be a factor in why Ruger is wanting you to pay for the barrel replacement.
I'm NOT,, repeat NOT accusing you of anything or lying or whatever. It's just that I have had many, many encounters with folks who swear that "Daddy bought this gun that way" or "My dealer sold me this gun and said it was factory" or other similar stories. I have seen XR3-RED grips with a red recessed eagle medallion that the owner swore were original factory items. Or the claims of a gun being shipped with a brass g/f and it's well out of the range or model that Ruger made.
Please do not take my post as being critical or anything. It's just a lot of my thinking on it and the potential variables as to why the gun has a bad forcing cone, and the current feelings by the folks at Ruger, combined with a bit of history of how they have done things.