Pmags are hard to beat, most of mine are pmags and hex mags. I've had 0 malfunctions with both using the 6.5 and 308. that's the fun with these types of weapons is the variety of stuff you can get for one. doesn't hurt to experiment with other mags. but if you don't want to spend extra money, i'd try a pmag and if it works i'd stay with it. There are some good steel mags out there too.C products defense makes a good one. just start with one brand and see if they work and buy more if they do. I don't know anything about the 260 but I imagine it will fit and feed similar to the 6.5.