What feature distinguishes the M4 from the M16 A2 as described?

• A. It has a collapsible butt stock
• B. It uses 7.62mm rounds
• C. It is fully automatic
• D. It uses a drum magazine

Answer: (A)

The feature being tested is how stock design impacts handling. The M4 uses a collapsible (telescoping) butt stock, which lets soldiers shorten the weapon for easier maneuvering in tight spaces and adjust the length of pull to fit different shooters. The M16 A2, on the other hand, has a fixed stock, yielding a longer, more solid platform but less flexibility in length. That collapsible stock is the distinct element that sets the M4 apart from the M16 A2. The other attributes listed don’t provide a unique distinguishing factor, since both typically use 5.56×45mm cartridges and detachable magazines, and neither is standardly issued as full-automatic. Drum magazines aren’t the standard configuration for these rifles.