While I have no zeal for the notion of the man having a registration of all my weapons, I did just spend a vacation day cataloging all my firearms by manfacturer, model number, caliber, serial number, and attached photos for each on a spreadsheet for insurance purposes. Should the token boating accident ever become a reality, it would be nice to have the claims adjuster on my side rather than assuming any inflated claim is bubblegum. The spreadsheet allows me to sort by header for my own organization, and lives on a zip drive with hard copy backup in fire/water proof storage. The household policy has always captured the additional value of inventory, but I wanted the specifics for my own CYA policy. The photos help substantiate any improvements beyond stock configuration, and can quickly jog one's memory without a rummage around the vault. Having my service rifle SN memorized back in the day was fine, but it was time for an upgrade better than memory alone...puts the mind at ease.