Sorry Linda, I was a bit slapdash there; the first delivery from the first order, after S&W started again following diversion of the earlier production to the UK, was 2200 revolvers.

UDF number 112 is S/N 693675, and not 693673 as you typed.
S/N 690876 has UDF number 811,

No, S/N 721300 cannot have been in the first shipment because its UDF number is 10538.

Unfortunately no record of the correlation between S/N and UDF number has survived. One can only work from examples seen or mentioned in the archives for some other reason. For example, S/N 697032 UDF 3822 was "found in the possession of a native in Zanzibar" in 1942!

Peter