Anatomy of a Centerfire Rifle Cartridge

Here is a great illustration from our friends at Cheaper Than Dirt.

Case - Usually made of brass and contains the powder charge, the primer and the bullet. Before development of the metallic cartridge, the term was used to mean a roll or case of paper containing powder and shot. Centerfire metallics include all pistol and rifle cartridges that have primers in the center of the base.

Bullet - A single projectile fired from a firearm.

Crimp - The portion of a cartridge case that is bent inward to hold the bullet in place.

Powder - The general term for any chemical compound or mixture used in firearms that burns upon ignition. The gases produced by this rapid combustion propel the bullet down the bore. One major type is black powder, which is a mixture of charcoal, sulfur and saltpeter. It's used in older cartridges. Another major type is smokeless powder, which is principally used in modern ammunition. It's a granular nitrated chemical compound.

Primer - The collective term for the chemical primer compound, cup and anvil. When the primer is struck, it ignites the powder charge.

Rim - The edge on the base of a cartridge case. It's the part of the case gripped by the extractor to remove it from the chamber. In some cartridges it also prevents the case from entering the chamber.

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- Greg