Let me see if I understand you. They offered a 50% reduced price for a replacement on a used barrel that had seen chambering to +p, 480 rds down range using long bearing bullets in an already hot 300RUM, and you feel like you should receive a completely new barrel free? Do I have that correct?
I've driven a lot of warrantied tires that did not live nearly as long as the claimed 50-70,000 miles, and at no time has anyone ever offered to replace the set for free nor did I expect it. Same with battery lives, etc, etc, etc. I have seen barrels burn out quicker than expected, and I have seen them last much longer than "normal" or expected. At no time did I ever think the barrel maker should have replaced for free any of those that died sooner than expected. Unless there was an "obvious" defect "caused by the maker", I just considered it the price of high performance or the sport we enjoy.
But that is just me.