Even though all manufacturing was moved to Huntsville in March of 2015, frames marked Charlotte were still being used up through December 2016 in Huntsville.  The first frames marked Huntsville start in January 2017.  All Smoke models are indeed made in Huntsville as they were introduced in September 2017.  Also, just because an R51 is marked Charlotte does not make it a G1.  G1s had a couple identifiers: R51 logo on the slide is in a different location and the sights do not have set screws.  The G1s also came in a bright green box rather than the new hunter green box. 

The Blue Book of Gun Values has some incorrect information - the G2 was reintroduced to original owners on June 23, 2016 and to the public on August 12, 2016. Production was suspended in fall 2018.

I think that you are right that at the end of the production run they started using any and all extra parts to assemble guns and get them out the door.  I also think that your pistol could very well be the factory prototype model for the "Smoke" color variation.  This could explain the out of sequence serial number, blemish and used status.  Either way, it is going to be difficult to verify any information on the gun now.

The first thing I would do to your gun, to make sure it works properly, is to trim the legs on the magazine followers.  This will solve most problems. https://www.youtube.com/watch?v=IZBnEgdQvUU

This post shows the other things to do to the pistol to get it ready: http://r51pistol.com/r51-general-discussion/steps-to-a-fully-functional-model-r51/

If you are interested in the timeline of NC to AL production, this is a post that will shed some light on the matter: http://r51pistol.com/remington-r51-facts-and-specs/a-brief-history-of-the-r51/

Gman, that is very interesting that your smoke model has the serial number H014XXXR51.  Supposedly there were about 65,000 total units produced.  It is hard to get information from Remington on the production because of the recall and other litigations.  The list that I have of known serial numbers is only 185 owners long, but a good sampling from Prototypes, NC Gen 1s, NC Gen 2s, Huntsville Gen 2s, and Huntsville Smoke models.  I haven't tried calling customer service since the sell off, so I don't know if it is an option anymore, but you used to be able to call and they would tell you the production month and year of your R51.  Your serial number would suggest a spring 2017 production.  Maybe your lower frame was held over until the fall of 2017 when smokes were sold.  Or it could be an early test design that was proposed before the actual run happened.  That would be very cool, the prototype smoke model! 

I have never seen a lower frame marked "HSV", but all smokes are from Huntsville.  I would be very interested in your co-worker's gun digest book pages.  You should post the scans for all to see.

Just curious about your purchase, did it come in the original Remington box?  Was the box marked with material #96234?

Nothing official other than replies from Remington customer service.  But then again, Remington was never forthcoming on the R51 since the beginning.

Received a reply from Remington, no more R-51 production.

Assuming you are right handed?

Welcome!  There is a lot of good information in this forum to get you going.  Aftermarket accessories are getting pretty slim since they quit making the gun in 2018.

More wood grips on ebay:

https://www.ebay.com/itm/Remington-R51-Wood-Grips/274531078788?hash=item3feb53d284:g:dcsAAOSwpBJfhGsE

Welcome to the forum.  Are you an R51 owner or just a fan?  Do you have any experiences/wisdom to share?  Let us know.  There is a lot of useful information on the forum.