Originally Posted by m102404
It looks like simply two slots cut into the side of the feed tube...the bbs feeding up would have to overcome the o-ring tension to make it up. Weak springs would likely blank fire. I'm sure they'd work with a Hicap.
Now that you mention the slots I feel completely in control of my understanding of the unknown design!
I bet that when the mag is inserted the feed tube is pinched together slightly. If the slots and o-ring are matched appropriately then there should be no o-ring in the way.
When the mag is not present the feed tube is not pinched together and the o-ring (well, the parts showing through the slots) retain the BBs.
No more 3-4 BBs dropping out the hop-up when you pull out a mag would be nice.
If you drop your mag...how do you clear your gun? Invert it and shoot out what's left?
Unless I misunderstand you, this is really the only safe way to clear an AEG anyway.
Regardless of the BBs dropping from the feed tube when mag is removed, in my experience there's almost always one left in there. Drop the mag, invert the gun, pull the trigger a few times = cleared.