Are mags interchangeable

Think so, as evidence, check out Hajimoto's website, pretty sure he sells a high-capacity aftermarket mag that fits both, at least that's what Casino7095 states in his Air Venturi Avenger Bullpup video. He uses Hajimoto's magazine in both so seems interchangeability in magazines, is likely. WM

Beeman, Benjamin mrod, avenger and gauntlet can all use the same mags

While all these air rifles have close dimensional geometry, it is not advisable to use them across multiple PCP's. Here is why. Each one of these air rifles has a slightly different barrel to mag well relationship and while a malleable material will be able to fit any one of them, if all of them are allowed to impart their tolerance differences to the same magazine, it will eventually fit most loosely, and only one properly. Our mags are designed to fit each PCP for their unique and slightly different geometries. So it has always been my advice to treat plastic/polymer magazines as a dedicated extension of the PCP it is broken into.