Winchester/Miroku 92 "pre-production" model

[hatman]

I've been on the hunt for a good 92 (either original or new) for a while now.
I just encountered what is purported to be a 'pre-production' model Winchester/Miroku.
It has a 20 inch octagon barrel and standard bluing.
The serial number looks like this:

000482
MYSAR

Supposedly the "SAR" indicates a pre-production model.
I sure haven't seen a new Winchester 92 with a 20 in octagon barrel nor such a serial number.

Should I have any concerns about a specimen like this one?  Thoughts?
Thanks

[Pettifogger]

If it is a "pre-production" model then how did the seller get it?  Factories don't usually sell pre-production models.  If it looks and feels like a regular Winchester/Miroku 92 and the price is right, it is probably OK.  If the seller is adding a premium to the price claiming it is "pre-production" I would want documentation.