[MaterDei]

Why are serial numbers always written like this?

1234xxx? Is it just because the last three digits are unnecessary or is there another reason?

Partly Cloudy,

MaterDei

[444]

The last three digits are unnessessary for the purposes the serial number is being posted for.
People don't want other people to know the serial numbers of their guns. One reason I have seen mentioned is that someone could report a gun stolen with serial number ________ that they saw posted on-line.

[Brian Dale]

It's meant to keep the exact serial number of one's possessions out of the hands of criminals, including gun-grabbers, while providing enough info with the first part of the serial number to determine such things as the date of manufacture. Nobody wants to have some criminal fraudulently report the owner's weapon as stolen, or have an opponent in a lawsuit (or other troublemaker) be able to claim that they've been threatened with or even shown a weapon because the owner posted a complete serial number on the Net.

Some folks think that this is going overboard; I don't. There are already plenty of instances of credit card fraud and identity theft in the world.

Edit: as usual, 444 is faster and more succinct than I. :)