I took a regular 308 accurate mag and put a primal rights 6br spacer and follower in it and did some feed lip mods to it to work and it works very well. I also took a .223 accurate mag and modified it to be able to run the Valkyrie. Theres a few threads the have options for a mag for the Valkyrie, I cant remember where but you can use the search and search for Valkyrie mags or lol something Valkyrie.