If you don't want to wait 6 months to get it back, pickup a Bartlein 5R .308 1:10 blank, and have a local smith true the action, fit and chamber the new barrel it for you. For $550-600 you could have a hell of a shooter. Or you could wait 6 months for Remington to email you back to tell you what you already know.
I hate to sound blunt about it, but I know I've been this route with my 700 .338 WinMag and debated and weighed all the options... Easiest and best option was to buy a new barrel off ebay in the chamber I was really wanting (7mm RM), and had my smith true it and put it together. Turned out to be the right choice. Took no time at the smiths and ended up saving me many a migraine even though it cost me money.
Sometimes its best just to cut your losses and figure out the best way to proceed forward. IMO, when it comes to bad barrels on rifles that cost less than $600 MSRP, sometimes it's best just to swallow your pride and open the checkbook.
My Browning 7mmRM I bought used, got about 100 rounds down range, barrel started wildly throwing shots. Had to eat that $600 and stick a new tube on it and pay the smith.
Bought a new Weatherby Accumark ($2,100 rifle)... Factory barrel started caving in. After years or stress and a complete pain in the butt, I finally had enough. Traded it back to the store I bought it from for a huge loss back before thanksgiving...
My examples are mearly to show that I do feel your pain, and have been through this myself on several occasions. I am not a well-off individual...But I do save for my hobbies. So I also understand the wanting to send it off for free perspective, too. I just don't think you'll like the outcome and it will probably end up just a waste of time. A new barrel and blueprinting has a much better chance of resolving your issue.