US Air Force M4 modification

https://aais.ria.army.mil/AAIS/Award_web_04/W52H0904D00860000/DAAE2003R0216/attach_exhib/Attach_010_M4_Spec_Mod.pdf

Is the above unique to the USAF or just mirroring other services?

Since the entire document is not there I cant say for sure, but to me it looks like they are now procuring weapons without a Carry Handle and are testing them with the BUIS prior to acceptance from the factory.

I believe this is the original contract:

https://aais.ria.army.mil/aais/award_web_04/W52H0904D00860000/000000.pdf