What does case obturation refer to?

Case obturation refers to the ability of the cartridge case to expand and seal the chamber during the firing process, preventing gas leakage and maintaining pressure behind the bullet. When a round is fired, the heat and pressure cause the case to expand and fit snugly against the chamber walls. This ensures that all the propellant gas is utilized to propel the bullet forward, improving the efficiency of the round. Once the pressure decreases after the bullet exits the barrel, the case then contracts back to its original shape, allowing it to be extracted readily.

This property is crucial for the overall performance of the ammunition, as effective obturation ensures that the firing process is safe and efficient. Understanding case obturation is essential for those engaged in ballistics and ammunition development because it affects not only the velocity and accuracy of the bullet but also the safety and reliability of the firearm.