I'm a little late on this thread and a new member. Here's what I can tell you about the USBP 50th Anniversary S&W Model 66 as I've owned mine since they were issued to us. I was stationed at Rouses Point, NY from 1973 to 1976 and coordinated the order for everyone at my station plus some other former Border Patrol Agents. We received 31 copies in my area out of the 3K+ that were made. The order was placed via a local FFL and received by him some time later and I was present when all the boxes were opened. To our surprise when we started matching serial numbers to names we found that most of the revolvers had the USBP serial number that matched the individual's radio call sign. We were part of the Swanton, VT sector which was Sector 2 with call signs starting at 200 for Chief and on down. Rouses Point station started at 210 and I was "217" which is the USBP serial number on my copy. We later found it that it was done as a favor sinve the national president of the union (National Border Patrol Council) was in our sector. The union, with the blessing of BP HQ in DC put this effort together.
Here's how they came boxed and, no, there was no Randall knife as part of the deal although I seem to remember the knife offered at a later date to be paired with the revolver. Outside cardboard box from Betts&Majors, Dallas, TX which was the S&W distributor at the time that the total order went through. The project number was CRP-1402 for the entire project. Inside the box is another lighted weight cardboard box containing the wooden commemorative box, also a side standard blue S&W box containing the revolver, and cleaning kit. How do I know this? I'm looking at it all right now including original paperwork as received. I can still read the original postmark on the outer shipping box-Jan.16, 1976. It took about a year and a half to get this project going and to receive the revolvers.
I have never removed the Goncalo Alvez oversized grips to see the serial number but my paperworks says 7 K 51 xxx.
Hope this puts new light into the situation as I was there and lived it. That being said and since I have only daughters and granddaughters who have no interest, the entire package is for sale so contact me if interested. I also have the USBP Commemmorative Model 94 Winchester carbine (Trapper version chambered in 30-30) We tried to get Winchester to chamber in .357 magnum but there weren't enough orders to get a special chambering run.
That's my story and I'm stickin' to it

PS: The project began with S&W offering a blued model 19 or the new, at the time, stainless model 66. Union members voted which one to get and the vote went for stainless. The reason being, there were about 20x more agents on the southern border who wanted to carry the revolver and stainless was much more resistant to their habitat. IMHO the blued steed with gold inlayed badge and text as a collector's item would have been a lot better. Those of us who had already done our time in Hell and transferred north were voted down. Don't think I ever ran into anyone that actually carried theirs.
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ADDED INFORMATION: Just to clarify some of the earlier posts, the Border Patrol badge "did not" have a serial number as INS (Border Patrol) did not issue them. The badge on the reverse clearly states " this badge conveys no authority unless accompanied by proper credentials". How do I know this, I'm looking at my old badge right now. Prior to becoming re-named Border Patrol Agents in June 1970 were known as "Immigration Patrol Inspectors" and I also have that badge sitting in front of me. When I left the BP I became a Treasury Special Agent and the whole world revolved around the badge number which was plainly in gold surrounded by blue acrylic on the front of the badge....again, looking at that retired badge right now.
The USBP Serial number on the revolver is on the left side rear frame and is USBPxxxx. Those numbers were random and had nothing to do with date of order or anything else. As I mentioned above, some of us in the Swanton, VT Sector received our radio number as our serial number only due to the fact our national union president was also assigned to Swanton Sector and had a lot of input on the program. Receiving your radio number as your revolver number was a big surprise when the FFL and I began opening all those boxes on his dining room table-he was the mayor of Champlain, NY at the time and firearms was more of a hobby than a business (probably wouldn't float in modern times)