I can tell you for sure that the 04 guns where not built in order...
basicaly what happened was we built them by color, some one ordered a red gun so we grabed a red body and put it in the build line and when we got to it it was built.
As for serial numbers, again they where puton the bodies, but some time 50 guns would be sent out to customizers and they where once again grabed off a cart that had random bodies on it.
The bodies where handled several times for serveral other process's after they came off the mill.
as far as I can remember , the only bodies kept out where special one or requested numbers by sponcored players, owners and gun techs.
Hope this clears things up and helps out a little bit.