Thanks, I was looking for too much clarity I guess. This is what got me thinking - Barrels proofed pre-1896 appearing a gun with a serial number from 1901 or thereabouts:
Post on the Reilly line from Toby Barclay:
"Argo44, I sold 35079 a few years back but checked my listing and the address was 277 Oxford Street. However the proof marks showed the gun was probably PROOFED pre-1896 so maybe made for stock and then finished and numbered accordingly." (my note: Reilly's shop at 277 Oxford Street remained open until about 1903; 35413 was the first Reilly I found with the address which succeeded 277).
And my reply:
Thanks Toby - .... It's interesting that the barrels were proofed pre-1896; Per the serial number you'd think it should have been numbered/finished about 1901-02 or so, depending on how many guns Reilly was selling (per a later post below, it looks as if he were selling about 130 per year from 1898-1903). If Reilly stockpiled barrels and actions, maybe that was how they were able to respond to orders with alacrity.