Gun Control & RKBA
In reply to the discussion: Ultimately this whole thread is offensive. [View all]MicaelS
(8,747 posts)(1) If they found cartridge cases of a particular caliber at the scene .i.e; 32ACP, .380ACP, 7.62×25mm Tokarev, 9mm, 9mm Markarov, .40 S&W or .45ACP, they almost certainly came from a semi-automatic pistol, or a sub-machine gun. Sub-machine guns fire pistol caliber ammunition not rifle caliber ammunition. Revolvers don't eject cartridges automatically, and revolvers that fire semiautomatic pistol ammunition are very rare.
(2) Because of the firing pin indentations on the primers in the empty cartridge cases.
Different brands and models of semi-automatic pistols create different striking patterns on the primers when each cartridge is fired. Many have a round firing pin with a rounded tip that creates a hemispherical dimple in the primer when the cartridge is fired.
Other pistols, like the Glock, use a striker instead of a firing pin. The Glock striker is rectangular in nature, and creates a rectangular mark. Once you have seen fired cases from a Glock they're instantly distinguishable from more conventional pistols. If the cartridge cases have that rectangular mark, then they came from Glock semi-automatic pistols.
See picture below. Case on the left is from a gun with a conventional firing pin. The case on the right came from a Glock. If the cases looked like the one on the right, they came from Glocks.