I have a coupe of comments and a couple of questions.
Comments first:
Since the rifle was smithed by someone unknown to all parties involved, its not surprising that Ruger is reluctant to work on it as is. If they can't fix it as is, you as the customer still remember Ruger could not fix it. With the internet especially, the details get lost and Ruger customer service becomes crappy to all who read your comments, intended or not to cast them in the light they become seen as.
Its like the old sign: Repair work - $50/hour. If you already paid someone else to fixed it - $75 per hour. If you tried to fix it yourself - $100 per hour.
And from their point of view, an improperly barreled rifle (based on action size) is not something they want in the market place representing them. Hence their offer to re-barrel or replace completely at a cost since they did not build the rifle in its current condition. For me that seems reasonable. Someone is going to charge for the work if you get it re-barreled. If they do it they want to be reimbursed or get paid for a new rifle if they send that to you. The current problem is not of their making.
I'm not saying you should do either and in fact I probably would just ask for the gun to be returned to me like you did. I agree that they should send the rifle back with no questions asked if that is what you want so long as the rifle is safe to fire. You stated that it fired fine. It is yours at this point in time and not theirs.
I would think that Cabelas would still stand behind the rifle and help you out unless they have an explicit limited guarantee on used guns like 90 days, etc. I've never bought one there so I have no idea.
As for questions:
1. Is the barrel a Ruger factory barrel or an aftermarket barrel?
2. Do 250 savage rounds feed from the internal magazine OK and does the bolt capture the round under the extractor from the magazine and feed the round properly into the rifle chamber?
3. When you say extract, does the bolt pull the case from the chamber and keep it retained under the extractor, or is the cartridge dropping off the extractor as the bolt is pulled back before it hits the ejector?
4. Can you see the ejector? Does it appear to be normal and will the bolt/extractor allow the case head to contact the ejector? (Same question again, I guess, but I'll leave it)
5. Have you tried cycling the bolt a bit faster on extraction since the action is longer? Does it make a difference?
I'm only asking these questions as the Ruger 77 is a controlled round feed action for the most part. IIRC, years ago they went away from that with a bolt design change for awhile, but I believe the current rifles, MK II and Hawkeye, are controlled round actions as are most of the old tang safety actions. During the change period, IIRC the bolt face contained a spring loaded ejector like the Remington ejector, for example. If the action is a true controlled round style action, and if the bolt cartridge extractor is in good condition, it should hold the cartridge intact until it strikes the ejector which is not a part of the bolt itself.
The reason I posed the questions is that hopefully the answers to them should pin point which is at fault, the extractor or the ejector. Or could something else be in play? And can the problem actually be fixed in the current way the rifle is configured or is the action length contributing in some way where re-barreling to a long action cartridge is possibly the only solution?
Anyway, just my thoughts and I hope you get the problem resolved to your liking.