Co-worker has an original Detonics Combat Master (manufactured in Seattle), but he's had an issue it.  

He only has two magazines and both magazines drop after 3-4 four rounds fired.  I haven't seen him shoot it, but recommended someone else shoot it to see if maybe he's hitting the magazine release.  I also thought maybe the release spring may be weak, but he said it's stiff and has solid tension.  He was thinking about tweaking the magazine cutout, but I recommended he get to a gunsmith first.  He's looking for a good gunsmith in the area and I may have a few leads for him.  

Anybody hear of this type of issue that "isn't" operated induced?  

ROCK6

It looks like it uses a standard 1911 magazine catch. My first step would be to replace the magazine catch assembly (mag catch, mag catch lock, and mag catch lock spring and see if that clears it up without dinking with the magazines.

If that works, you can add / subtract parts to determine which was actually the culprit (weak or modified mag catch spring, damaged magazine catch etc.)

Yeah, that was my initial advice after telling him to have someone what him shooting and see if he somehow hits the magazine release (I've seen that happen before).