The Ruger No.1 is a Bill Ruger designed falling block rifle manufactured by Sturm, Ruger & Co. since 1967. The No.1 has been designed with a Farquharson style hammerless falling block action and has a capacity of only one shot.
The Ruger No.1 has been designed around the Farquharson-style hammerless falling block mechanism (originally designed for the Farquharson Rifle), which consists of a metal breech block that slides to cover and uncover the breech when the lever, located around the trigger guard, is pulled. This allows one shot to be loaded into the breech before a seal is formed by the block, meaning that the receiver effectively becomes a single piece of metal until the lever is pulled down again.
The No.1, as suggested by the Farquharson-style hammerless falling block action name, has it's hammer covered by a plate. The No.1 was also designed with a shotgun-style tang safety, designed to operate with the hammer and sear to prevent accidental discharge. The extractor system has been designed with the ability to adjust the extractor effectiveness and has been designed with the intention of being as easy to use as possible.
The Ruger No.1 is a highly popular firearm, used in a variety of hunting applications. This fact has meant that the No.1 will accept virtually any calibre (provided the customer specifies what they intend to use the No.1 for) ranging from the relatively small .218 Bee to the comparatively huge .460 S&W Magnum, with virtually every cartridge and calibre size in between being usable.
Other notable cartridges that the No.1 can fire are the .45-70 Government (a cartridge which has existed for over 140 years), .223 Remington (as most other "Varmit guns" do), .357 Magnum (the infamous police cartridge) and the various Ruger made cartridges.
The Ruger No.1 has become the most popular single-shot rifle of modern times, many heralding the No.1 as the firearm which reignited the single-shot rifle market. This was not the first time Ruger has reignited (and in many cases dominated) an area of the firearm market, the Ruger Blackhawk (which virtually rebuilt the Single Action revolver market) being a prime example as was the Ruger Standard (which dominated the .22 target pistol market), both designed in the 1950's.
The No.1 is renowned for its robust design and strength, specifically the falling-block mechanism which Ruger's own Lenard Brownell commented: "There was never any question over the strength of the action. I remember, in testing it, how much trouble I had trying to tear it up. In fact, I never did manage to blow one apart.".