Gravity can let the pellet fall back out the mag if the gun is being held upwards while cocking if your mag does not hold the pellets tight, and a few don't. This is before it is pushed into the barrel where it will stay. 90% of people never experience this if they shoot on a range as they are normally horizontal more or less, but in the field it can be different. Daystate mags seem to have their own personality, I've got some I don't even think about, yet others I would not use for target shooting as they open the groupings by half an inch - no big deal in the field, but for paper it's a waste of time. Once you know about it you can "lock n load" accordingly
James