Hammerless

A hammerless firearm is a firearm that lacks an exposed hammer or hammer spur. One of the disadvantages of an exposed hammer spur is the tendency to get caught on items such as clothing; covering or "bobbing" the hammer by removing the spur avoids this tendency.

Early hammerless designs

Early caplock firearms, patterned after their flintlock ancestors, had exposed hammers. The conversion was done by replacing the flash pan with a nipple for a percussion cap, and the flintlock's cock with a hammer to crush the cap and ignite the powder. The hammer was on the side of the firearm, easily reached for priming and cocking.

The earliest cartridge firearms simply copied the older style of action; the .45-70 "Trapdoor" rifle and most early cartridge double-barreled shotguns are good examples of this. In these designs, the loading of the cartridge(s) and the cocking of the hammer(s) were separate operations. While rifles evolved away quickly away from these early breech loading designs, the double barrelled shotgun retained its popularity, and, for some time, its exposed hammers.

American inventor Daniel Myron LeFever was the first to develop a "hammerless" shotgun in 1878. It used internal strikers that were cocked manually, but in 1883, he developed a version that cocked the strikers automatically as the action was closed. This type of hammerless action, or the similar cock on open variation, is nearly universal in modern double barrelled shotguns.

Pump shotguns

Early pump action shotguns, like the lever action rifles that preceded them, had exposed hammers. Most famous of these is probably the Winchester Model 1897. Like the double barrelled shotguns, soon the early pump shotguns were replaced by models that enclosed the hammer completely in the action. Modern pump shotguns, with the exception of replicas of older exposed hammer designs required in Cowboy action shooting, are all hammerless.

Handguns

While shotguns have gone almost entirely hammerless (inexpensive single shot models being the main exception), handguns are available in significant numbers in many different forms, with or without exposed hammers. Striker fired guns, which are becoming more common, have no hammer, while many guns that do have hammers, such as revolvers, are available with the hammer shrouded or with the spur bobbed off. To be able to conceal or bob the hammer of a revolver, it must be a double action design, and most automatic pistols with bobbed or concealed hammers are also double action.