Ain't gonna happen; these guns are "dead", and too small for such ctgs. There's plenty of small semi-autos on the market in those calibers...

Yes, for now the gun is dead.  Vista Outdoor came and took all the manufacturing equipment out of the Huntsville plant.  So it would be hard to start production back up.  Maybe at their next 100 year celebration they'll bring it back.  However, I disagree on the "too small for such cartridges."  Remington themselves announced that it was part of the plan to have other calibers in the R51.  And yes there are plenty of conceal carry pistols out there in .45 ACP, .40 S&W, and even in 9mm Luger.  Some even smaller than the R51.  Heck, the R51 with all its issues and bad reviews still sold out at every gun store.  Just curious about what the folks in the Ilion, NY plant are doing.  They supposedly went back to work at the beginning of March.  Did Ilion get rid of their equipment to make 1911s when the Huntsville plant opened?  Hope not.

@Gorillaman- after some further research on the out-of-sequence serial number on your pistol, I have found something very interesting.  In the 2018 Remington catalog, where the Smoke made it's first debut, they have, what I believe, is your R51 photographed in the catalog.  I think we can say that you have the prototype Smoke model R51.  That, my friend, is a collector piece!

Hopefully Roundhill will do something with the R51 in the future now that the users have figured out how to make the gun function properly...  Still hoping for the R52 (.40 S&W) and the R53 (.45 ACP).

Nice!  Way to go.  I was considering reaching out to the seller too.  Hope you got a good price.

Love finding a good deal!

Found this video on the tube.  Hope it helps you out.

https://www.youtube.com/watch?v=l92x4--NWx0

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 brighter kelly green box rather than the new hunter green box. 

The Blue Book of Gun Values has some incorrect information - the G2 was re-introduced 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, new label over original label, 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/