Redneck,
Thank you for the reply. I honestly don't remember if Jack First asked me about S/N. This is one of those "back burner" things, and I bought the extractor a long time ago.
I can compare them side by side, and with the info you have given me about S/N number and part number, maybe I can find a part number on the envelope it came in (plus I sometime store receipts with the parts.)
I vaguely recall something about a difference, perhaps having to do with the countersunk hole that the spring loaded plunger pushed into in order to force the extractor to the "rest" position?
I hope this is the last M100 I ever have to deal with. Between it being one of my father's guns that I didn't like, and now my friend dying unexpectedly, I particularly want to be shed of this one!