When making a gun based on a standard design in a factory production , the parts are being machined and passed onto the benches for build up . As a result there will be a stock of barreled actions of differing bores and barrel lengths .
When an order for a non standard gun ,ie specific stock measurements or engraving is made this can be put into the production line as soon as it has been received . Thus a "special order " can be delivered rapidly , assuming the maker dose not have a long pre order waiting time , which at the time of this gun would be unlikely.
Any one making a gun today or should I say commissioning a gun today using outworkers will take far,far longer than a factory that did all work "in house".
I would think that a Webley 700 , for instance, could have been built from machined parts to delivery in 10/15 working days [ had it had been attempted ] but needing the attention of 18/20 individuals and a well equipped factory for its making .
