I'm thinking of buying one of these rifles, spinning the barrel off, selling the old barrel, and spinning on a 6.5mm cartridge. I'm torn between the 6.5 creedmoor and the 260 remington. The question I have is, how well do these magazines from the FCP-SR work with either the 260 or 6.5 creedmoor. I plan on shooting the long berger hybrid 140gr or the 142gr SMK.