If you look at the quick cap magazines, basically you pull the cap out just like the standard magazines, but it's on a hinge, so it won't/can't fall off. You move it to the side and reload.
However, a huge disadvantage is that because the magazine can never block the flow of paintballs into the breach, it can't be dismounted from the gun without removing the pins that hold it onto the top of the gun.
So in a nut shell, you won't ever lose the back cap, however you can't swap out loaded magazines.
These are on my Warsensor WSP's.
Face full of bolt is the only way to play. Autococker FTW.