I picked up a US Govt contract 12Ga Mossberg today at Keepshooting (great deal by the way) and noticed that in addition to standard serial numbers, it also had UID markings. Since i work for DoD, I'm familiar with the system since it's required on all new contracts. It's a 2D dot matrix that contains manufacturers and contract data that is deciphered with a code reader. However, it's the first time I've seen it on a firearm. Has anyone else seen these?