This is my USA made HK45 pistol with German extended/threaded barrel and Surefire X300 light attachment. The magazine was a standard German 10 round magazine. On the 7th round, the magazine dropped unexpectedly. This happened at least 3 or 4 times during the course of my visit to the range that day. I've only put 125 or so rounds through the pistol thus far, and this hasn't been an issue save for this most recent trip. I noticed that my finger was slipping on the trigger during recoil and could possibly have hit the mag release. My guess is it's a problem with the way I grip the gun, as the gun had an issue with not locking open on the last round when I was resting my left hand thumb on the slide stop previously. I am of the opinion that the gun is picky with the way you grip it. I've also heard of people decocking the gun during recoil if they rest their thumb on the safety/decocker.