from the centerline of the barrel. These production methods are generally simpler and reduce production costs. It is generally recommended not to excessively "dry fire" rimfire firearms (ie firing without a chambered round) as it is possible for the firing pin to strike the face of the camber and deform it or damage the firing pin. Historical cartridges In 1808 by the Swiss gunsmith Jean Samuel Pauly in association with French gunsmith François Prélat created the first cartridges to integrate a primer and be self-contained. The paper cartridge used a metal base with a through-hole coated in a percussive priming compound. Pauly also developed a breech-loading shotgun for his cartridge, using a firing pin and external hammer. The Dreyse needle gun of 1836 uses a paper cartridge with a priming as part of a sabot which cradles the projectile and is forward of the propelling charge. The needle-like firing-pin projects from the bolt-face and pierces the cartridge when the breech is closed. On firing, the spring-loaded needle strikes the priming in the sabot. Unlike Pauly's cartridge, which was not widely accepted, Dreyse's rifle was adopted by Prussia as its infantry service rifle. It was the first military breechloader to use a self-contained cartridge and consequently, the first to employ a firing pin. The pinfire cartridge patented in 1835, uses a metallic cartridge with an integrated firing pin located radially near the base of the cartridge. The pin needs to be aligned with a corresponding slot in the chamber; a disadvantage compared with rimfire and centerfire cartridges that followed and that are also safer. Side-lock hammers Early rifle designs that fired metallic cartridges typically used a side-lock mechanism, with the hammer mounted to one side rather than inline with the axis of the barrel. In the trapdoor Springfield Model 1865 (and similar) the rear of the firing pin tube within the breechblock is angled away from the centerline of the barrel toward the hammer. The Sharps rifle uses a firing pin block to solve this alignment problem. The block sits within a recess in the breechblock. When struck by the hammer, the whole block is propelled forward. That part of the block with the firing pin sits on the centerline of the barrel and strikes the primer. Fixed firing pins Many revolvers use a firing pin that is fixed to the hammer. Simple blowback sub-machine guns that fire from the open-bolt