Just going to give a quick update regarding the magazines mentioned in the video. They are junk. In one of them the follower jammed with a mere 50ish bb's loaded. So I go about dismantling it to undo the jam. Really, really bad move. 4 screws to remove, crack open the shell slowly to avoid the spring launching into outer space, no dice, it does it anyway. 5 SPRINGS. What the hell?! There is no way to rebuild them without 6 or so hands, its just such a stupid design. SO. If you have bought some already, if it breaks, bin it. Get a decent mag, never ever consider another pack of these again.
NB: I spent nearly 2 hours trying to rebuild it before it ended up in the bin.