Aside from a special designation, any firearm, that has turned 50 years old, is C&R eligible. If it was made in '62 or earlier, you're GTG.
The first of the Colt AR-15's are coming of age...
07 FFL /Mosin-Nagant Custom Shop/Bent Bolts
Genuine Cerakote Applicator- ALL FIREARMS
General Gunsmithing and Re-Barreling