What is the relationship between barrel length and velocity?

The relationship between barrel length and velocity centers on the principles of ballistic performance and the dynamics of projectile acceleration. Longer barrels typically allow for higher velocity because they provide more time and distance for the expanding gases, generated by the burning powder in the cartridge, to push the bullet down the bore. This extended interaction allows the projectile to gain speed before it exits the barrel.

As the bullet travels down a longer barrel, the gas pressure continues to exert force on it, which contributes to increasing its velocity until it reaches a point of diminishing returns. After a certain barrel length, additional length can offer minimal increases in velocity, but generally, a longer barrel can facilitate higher velocities compared to shorter barrels.

While the other options suggest concepts that may apply in specific contexts, they don't accurately represent the general understanding of how barrel length affects bullet velocity. Shorter barrels tend to limit the duration of gas action on the bullet, and claiming no effect fails to acknowledge the fundamental principles of physics in ballistics. The idea that longer barrels are less accurate also diverges from established performance metrics, which often show that barrel length can contribute positively to accuracy at distance due to improved stability and consistency in the projectile's flight path.