Upper Markings Question

[Fisherman24]

Hello, hoping someone on here can provide me with some insight. I have two C8 surplus uppers, both seem to be identical but the markings seem to differ slightly on both. The gas block on one is marked D99 R1 1 and the other is D99 R1 2. The barrels also have different marks - .556 26330 and the other .556 25435. Just curious if there are any differences between the two?

 

[lerch641]

The numbers after the calibre are CAGE codes, nothing to worry about there.

 

[Fisherman24]

Gotcha. Any idea what the codes on the gas block mean? Thanks

 

[Rebel Rouser]

The fbs markings are all different, Diemaco had various contractors.

 

[Fisherman24]

Great info, thanks!

 

[*crash*]

The 2 indicates that the chamber had been increased total 3 thou due to issues with the C8 on full auto. When the chambers were increased they tested them with the assaulters at the "Hill". They loved them after the changes. The other numbers are lot #'s.