My Son recently got a few Airsoft guns for his 14th Birthday and I have already had to troubleshoot both in the 2 days he has had them.

I figured I would document what I did in case anyone else gets this problem since apparently these are both rather new guns.

Umarex Glock 17, otherwise known as Elite Force Airsoft Glock 17
    This one had a random bb stuck along the side of the magazine that prevented it from being removed from the handle.  It only came out about 1 inch.
I fixed it by fully removing the fill cover from the bottom of the magazine "after opening the cover, pull down on that little slide again and the cover will slide off".  I then pushed the magazine as far into the handle as it would go.
I then cut an extra wide shim from a pop can.  "i cut it from around the can since it was longer that way"  it needs to be able to fit across the front of the clip covering the spring and wrap around about 1/2 way on each side.
Push it all the way in and then remove the clip.  it wasn't that easy as I had to pull the clip out a little while wiggling the shim in and trying not to slice my fingers open on that shim.

I'm still not exactly sure where it was stuck, either against the outside of the spring, or in one of the indents that the magazine release goes into.

I'll upload some photos shortly.