GRAVmags, saw `em, was curious, noticed they be 3D printed and figured the only way to find out was to get one. Liked it but checked for other opinions and found nuthin` so thought would give some feedback... Bottom line? Very happy, no snag ups and no regrets, tho` I noted even the maker reports problems with some pellets, but to be fair he names them [check the site if you need more info on this, I won`t put a link in case any numptys think this is advertising] - my Accupels + Diablos worked fine however, no jams, no hassle, no pellets dropping out. Fair play. BTW, mine is on a steel breech with standard bolt. Now mine, a 9S, was fitted to a Crosman 2240 which has standard 11mm dovetail, and I don`t even know if they make `em for bigger rails to be honest, but they do do .22 + .177. I also fitted a scope with no prob over the mag, but I admit I had to chose scope carefully to ensure snagfree installation. No expensive stuff mind, it`s only a Ratbuster after all. Anyhoo, hope this helps anyone who been wondering about `em. Stay safe playmates!