Don't forget that changes to the proof laws has to be made by act of Parliament so nothing could change overnight.
Argo: There's your answer. I think we all applaud your desire to be extremely anal with the SN's and dates of production . . . but it ain't gonna happen. Without a date code--preferably one like the Germans use, with month and year--there's no way you can nail it down very closely. Then there's also the question of when those guns were sent to the proofhouse. No way to be sure, for example, that SN 342 was proofed before SN 356. The assumption is that it's all done in sequence. But we have no way of knowing that for sure, unless you can get a copy of a proofhouse log book. Assuming one exists.
