Scott, I've had similar issues with my Mk46, so I know your pain. Some things to check: The hop-up chamber can sometimes sit a bit odd with the metal bracket at the top of the mag well. The design allows for some twist, so even though it's flush against the gearbox and in those slots it can still be out of alignment. Check inside the mag well and make sure you can see all the way into the hop-up chamber. If it looks like more of an oval opening than a perfectly round one, try removing and reseating the barrel and hop-up to get a better fit.The STANAG adapter on the A&K magazine isn't the most precise piece of plastic, and the mag release on the gun leaves a lot of wiggle room. You might need to play around with how the mag is seated. Mine doesn't like to be pressed all the way in; I have to seat it firmly (pressing all the way up towards the chamber), and then tug down slightly on the STANAG adapter so that the mag release rides at the top of the adapter's indentation. It seems that this might be another loose tolerance with that plate at the top of the mag well, were the feed tube will jam the mag. Try moving this adapter around slightly while it's in the gun to see if some position allows it to feed.You mentioned that BBs do come out of the magazine when it's removed, and this is another wise thing to check. Make sure you're giving it a good few seconds on "Auto" to prime the tube and get enough BBs loaded into the system. Also make sure you've got enough BBs in the reservoir; since there's no spring, it relies on the last several dozen rounds to apply pressure from the winding mechanism into the gun.I hope some of these troubleshooting steps help.