They don't thread the barrel with it still attached to the receiver. If you don't send them a bare barrel, you'll be paying the $50 dis/re fee.
AR15/AR10 Barrel Threading $65.00
This covers cutting/crowning as well as threading. This service is for any AR15/AR10 barrel once it has been removed from the receiver. AR barrels with the FSB in place are covered under this service/fee. These threads will be the perfect size and will be concentric to the bore. This service also covers stripped non tapered barrels of other varieties. If the barrel will not drop through a round hole, with a diameter slightly larger than that of the barrel, you need to select the non AR15 threading service. If sent as a complete upper, the Disassemble/Reassemble service is required as well. Gas port work is included when necessary.