I heard back from S&W customer service this morning.
Date of manufacture is May 2015. Which is a bit of a surprise. It must have been hiding somewhere all those years!
Product number is 108186, so just a plain 5946.
There were significant quantities of 108176 5906 and 108186 5946 sold off in the 2019-2022 time frame and possibly as early as 2016.
I have a 5946 VJP356x 108186U bought NOS (surplus) in 2022 with a Box End Date of 011419 but SW says manufacture date was 5/2009. Oddly enough I also have a 6946 VJP358x (16 digits later) dated by SW as 1/1998.
I also saw a similar 5946 VJN97xx 108186U with the same Box End date of 011419 but dated by SW as 7/1998.
One seller had an inventory list of 5906 from which you could select your s/n. These included KLF, KMF, KNC, TDP, VCZ, VUV, VZB, and VZC - all with Box End Dates 011119, 011419, and 011519 and Product Code 108176U.
And I have also seen a number of 5946 in the UCV, UCW, and UCY series with "Caution" slide markings and presumably without Mag Safety - all with Box End dates 040716 and Product Codes 149332. I confirmed manufacture date of one with SW as 4/18/2016.
Best I can figure based on other info is that:
1. SW assigns s/n to frames when frames are produced.
2. The s/n sequences may or may not be of the same pistol configuration.
3. They are assembled as orders come in.
4. If there is no immediate need the parts may sit unassembled until the need arises.
5. In the case of Special Orders, parts may be set aside as spares or in anticipation of further orders.
It appears these pistols sat either assembled but unsold, or in parts kits unassembled after the "end" of 3rd Production pistols.
At some point, potentially at the end of 5946 listing by NYPD as an acceptable pistol, or when clearing out other residual inventories, they were completed and subsequently sold off to various distributors.
