Maybe a case of minimum spec. cases and maximum spec. chambers? I had a Ruger .270 that misfired with a few different brands of factory ammo. After visiting 3 different "gunsmiths" and trying various cures it still misfired. Many don't want to (or can't) REALLY get to the bottom of a problem like this. They try a series of wild azzed guesses (that they charge you for) then, leave you hanging.
I really don't think it's as simple as Remington Corelokt ammo being defective. I'd be leery of any rifle that "just won't fire using brand X ammo". Maybe a chamber cast would help determine the problem.
