What is the primary function of the extractor in the slide assembly?

The primary function of the extractor in a semi-automatic pistol like the M9 is crucial for the effective cycling of ammunition. As the slide moves during the firing cycle, the extractor plays a key role in extracting the spent cartridge case from the chamber after firing. It grips the rim of the case and pulls it rearward, allowing for proper ejection of the spent casing from the ejection port. This process is vital for chambering the next round effectively and ensuring the gun continues to function reliably.

In contrast, while the other functions mentioned are important components of the pistol, they do not pertain to the extractor. The extractor does not hold the chambered round in place; that is the function of the chamber and the magazine. Additionally, it does not provide safety during firing, as that is managed by mechanisms such as the safety and firing pin block. Lastly, securing the firing pin assembly is a role fulfilled by different parts of the firing pin mechanism, not the extractor itself.