Which component expands during firing to assist the seal created by the gas-sealing features?

Which component expands during firing to assist the seal created by the gas-sealing features?

• A. Rotating band
• B. Eyebolt Lifting Plug
• C. Obturating band
• D. Fuze Well

Answer: (B)

Gas sealing relies on the obturation band. When the round fires, the propellant gases push behind the projectile and the obturation band yields and expands against the bore walls. This outward deformation fills gaps between the projectile and the barrel, creating a tight gas seal so most of the pressure drives the projectile forward rather than leaking around it. The other parts mentioned have different roles: the rotating band primarily engages rifling to impart spin, and the eyebolt lifting plug is associated with handling or the fuze area, not with forming a bore seal.

Gas sealing relies on the obturation band. When the round fires, the propellant gases push behind the projectile and the obturation band yields and expands against the bore walls. This outward deformation fills gaps between the projectile and the barrel, creating a tight gas seal so most of the pressure drives the projectile forward rather than leaking around it. The other parts mentioned have different roles: the rotating band primarily engages rifling to impart spin, and the eyebolt lifting plug is associated with handling or the fuze area, not with forming a bore seal.