unopened 1984 Lake City box, the 30 loose rounds, and the Hollywood Blank Firing Bushing/Adapter together as a package deal 

1. Ammunition Box
• Component: An unopened, original box of 20 Cartridges, Blank, 5.56mm M200.
• Details: This is standard-issue military blank ammunition. The lot code printed on the box is LC-84L021-334, which indicates it was manufactured at the Lake City Army Ammunition Plant in 1984. It includes the safety warning, "DANGEROUS WITHIN 20 FEET."

2. Loose Ammunition
• Component: 30 loose 5.56mm M200 Blank cartridges.
• Details: These feature the distinct, extended star-crimped neck design characteristic of standard military blanks. 

3. Headstamp
• Component: The base of one of the loose cartridges.
• Details: It features the markings LC 84, which perfectly matches the box details, confirming that these loose blanks were produced at the Lake City Army Ammunition Plant in 1984. 

4. Metal Adapter Device
• Component: A internal "Hollywood" style Blank Firing Adapter (BFA) / Blank Firing Bushing.
• Details: Unlike the bulky external red or yellow clamp-on BFAs used by the military for field training, this compact, threaded device is designed for theatrical, movie, or historical reenactment use. It threads directly into the muzzle or drops inside a standard A2 flash hider. 
• Function: It creates back-pressure by restricting gas flow through a small internal orifice hole (visible in your first image). This traps enough gas to cycle the semi-automatic or automatic action of an AR-15/M16 platform rifle when firing projectile-less blanks.