I'm assuming your mag is the type that has an automatic advance device (ATD) integrated with its drive gear, right? Lucas
ATDs have a built-in extractor, and as a result it should first appear to jam as it unscrews, and then pop the drive gear off, if all is proper.
The hex-headed center "bolt" of the ATD is actually a tube nut, the open end of which is threaded 3/8" BSF to match the male thread of the K2FC's armature. The shank of this tube nut is threaded with a reverse thread, which is fundamental to the operation of the extractor function.
It works like this:
- As you undo the tube nut, it unscrews from the male armature thread on the mag
- The tube nut will unscrew until the reverse thread contacts the (hidden) underside of the ATD's yoke
- At this point, the tube nut will stop turning because it has jammed between the two threads
- You unscrew the tube nut with as much torque as you can muster by hand, which pre-loads the taper
- if you can't pop the ATD off the mag's taper at this point, a light rap on the hex head of the tube nut will shock the ATD off
It is vital to be gentle when tapping the tube nut, as you can damage the mag's internals ... this works only because the taper has been pre-loaded by the extractor mechanism.
I suspect your extractor is not functioning because the reverse thread on the tube nut is stripped, or some other problem is preventing the extractor from functioning as it should.
I hope this explanation makes sense ...