Rimless Pistol Cartridge: The pistol has an extractor claw that hooks over the rim to extract the spent case from the chamber after it has been fired. The cartridge is said to be rimless if the extractor groove is machined into the head of the case so the rim is the same diameter as the adjacent part of the case. Most modern automatic firearms use rimless cartridges and have a long enough surface for cartridges to lie or stack side-by-side in a magazine without risk of interference during the feed-stroke.
Revolver Cartridges: There is a rim at the back end of the cartridge that fits into the rim-stop ledge at the rear of the revovler cylinder that prevents the cartridge from moving forward when fired.
Dummy Cap Shells