Daniel Defense 5.56 NATO (5.56x45mm & .223 Remington) / 300 Blackout (7.6x35mm) full-auto compatible, M16 Profile, complete bolt carrier group assembly.
CARRIER
Machined from 8620 steel
Heavy Phosphate Coated
Chrome lined
Properly staked gas keys
Made in the USA
BOLT
Machined from Carpenter 158 Steel
High Pressure Tested
Magnetic Particle Inspected
Shot Peened
Heavy Phosphate Coated
Extractor Booster
Made in the USA
TEST FIRE DISCLAIMER:Many of the manufacturers whose products we carry will have a standardized test fire protocol for not only their complete firearms as well as parts such as upper receiver groups and bolt carriers. Because of this test fire protocol, some items will show evidence of the test fire process such as brass and carbon residue on internals or brass markings on case deflectors.
All around good experience. 
