Don,

No, it is not factory original.  A good friend of mine showed that rifle to me at the Big Reno show a few years ago (he was interested in buying it).  We ran the serial number with Jessica (she was at the show), and it does not letter with that butt plate (and a few other things that I can not remember).  The butt plate was the focal point of the conversation when I had it in my hands.

Bert