Good point Chuck. Courtesy of Dr Jim from the LCSCA FAQs
In most cases, more information is available for shotguns made between 1918 and 1950. In addition to the information for the early guns, the books
may include dates of starting, proofing, patterning, finishing, and shipping. The name of the company to which it was shipped and the order number are usually in the records. Occasionally, the name of the person ordering the shotgun will be noted, but many shotguns were ordered through a local or regional sporting goods or hardware company. In those cases, the name of the final purchaser was not recorded in the ledger. The shipping records usually contain a list of the options (such as REOBV which stands for regular weight frame, automatic ejectors, selective Hunter One-Trigger, beavertail forend, and ventilated rib) and occasionally contain special order information (such as a initials engraved on the trigger guard.)
We've got a parallel thread going on the LCSCA Forum, but I've not heard from Dr Jim if he has run across a .410 special order chamber length in the shipping records
http://members.boardhost.com/lcsmith/msg/1517270174.html 
