So after contemplating this all afternoon, these are my options...
1. Return the barrel to Questar for warranty with LMT. There are a few problems with this. For starters, I don't think they like me anymore - and since they genuinely don't feel bad about any of this - I can't really imagine they'd want to resolve this expeditiously for me at this point. Their 4-12 week estimate is also probably "best" case scenario (I'm thinking snow). There's also the issue of the barrel itself: this was apparently part of a limited run of 50 barrels, so the chances of finding a replacement are slim. So if they end up refurbishing it, and this was the condition it arrived in... what will it look like when I get it back?
2. Dispute the credit card charges. I've only had to do this maybe once, twice in my life - but this is certainly an instance where it warrants a third occasion. And I'm fairly certain I'm patient and persistent enough to prevail...
3. Wait for this thread to take on epic proportions and see if Questar responds publicly or offers an alternative (hint: while I don't expect Questar to lose money to keep me happy, providing me with a discount or the barrel at cost isn't an unreasonable option, either).
4. Shoot the crap out of it. Accuracy be damned! And every time I'm out shooting and people ask to check out my "cool LMT", I can point out the truly awesome barrel that Questar provided me! They say there's no such thing as bad press, and word-of-mouth is always the best advertising!
I'm leaning towards a combination of #3 and #4 at the moment, mainly because I had to initiate the call to Questar (even though in reality, they should've gotten in-touch with me after I indicated there was indeed a problem). And if they were genuinely interested in resolving this, they'd have figured out that it wouldn't have taken very much to make me happy... little things like "we're sorry about this", "don't worry - we'll take care of everything" and "we do appreciate your valued business".