For the PRC, you won't really need to go longer than the "stock" magazines allow for long action cartridges. That said, both Hells Canyon and Mountain Tactical have mags that will fit the stock bottom metal (as well as real metal replacement bottoms) that are better, at least in the sense that they are metal, than the factory mags. If you want a higher capacity AICS type mag, then yes, Redsnake and Atlasworx are good choices. With all that said, the factory mags have never let me down. I'm using factory 30-06 mags for my 6.5-284. For the PRC you may need WSM mags, but don't sell the factory jobs short.