I found out that C-Products makes Duramags for .204 Ruger, but only in 5- and 10-round sizes as far as I can tell. I'm thinking of picking up a 5-round for public land and two 10-rounds for target shooting. People say their big .223 mags work for .204 Ruger. I may get a couple. If they don't feed, they'll still be good for .223, and you can't have too many.