Abstract: A conversion device for converting a firearm designed to fire a cartridge of a certain size and caliber to another size and caliber cartridge is disclosed. In some embodiments, the conversion device is suitable for converting an AR-15 type firearm to be able to fire .22 caliber cartridges. Disclosed embodiments of the conversion device 100 may comprise an appropriately sized chamber insert 1 to fit in the chamber of the firearm, a bolt 2, an extractor 4, extractor plunger 3, extractor spring 5, firing pins 6, firing pin springs 9, a bolt spring rod 10 and block 11, a bolt return spring 12, slide rails 14, lock rings 17, and lock pins 15.

Abstract: Embodiments of a magazine 10 for storing cartridges 30 for use with a firearm are disclosed. The magazine 10 may include a stack divider 50 that creates at least two spaces for stacks of cartridges 30. The magazine 10 may also include feed lips 40 that have an entry point 41 sized to allow the cartridges to be loaded with a single straight-in motion.