My CYMA AR47 came with a bunch of CYMA midcaps, they feed perfectly with .20s and below, but anything .25 or above and they only feed about 1/2 of the time, I tried an old hi cap magazine I had and it fed perfectly with even with .30s, (the hi cap couldn’t feed fast enough for full auto though) so I’m assuming this is a magazine issue but I’m not entirely sure what mid caps can feed higher weight bbs, these are the first midcaps I’ve ever owned.