I can only write with a degree of knowledge on two gunmakers.
Frederick Beesley had a gun ledger in which his guns were added at the time they were begun in his workshops or bought in to stock, if supplied by another. The gun details were recorded on the left hand page and a serial number allocated at that time. On the right hand page the date of sale, name of first owner and retail price were recorded. We know he also kept a day book, a cartridge register and suspect he had a separate ledger for pistols. With the exception of the gun ledger, the others were in all likelihood destroyed by the bomb that landed on the 7 Bury Street premises in 1940, after Beesley had been bought by Grant & Lang.
The other ledgers I have viewed in some detail are Purdey's for the 1870s-1890s, where the serial number was allocated against the gun at the time of order, often without any date. I found it better to more accurately date the guns from the separate barrel regulating books, which recorded the date on which the nearly finished gun was tested on the range.
Tim
