July 13th, 2020


korth revolvers and rebounding hammers

Korth revolvers feature the peculiar German implementation of the rebounding hammer, an international design that dates back at least to William Bardell and William Powell from Aston, Birmingham, with patent No. 2287 of 6 September 1866. However, Wolverhampton lockmaker John Stanton takes the credit for the type of rebounding lock found on most hammer guns encountered nowadays, as refined in three of his designs. The first, No. 49 of 8 January 1867, received only provisional protection and used an external spring to lift the hammer to half-cock. Very shortly after this Stanton secured a second patent, No. 367 of 9 February 1867, in which the return of the hammer to half-cock by the mainspring is achieved by lengthening one limb of the mainspring at the top in a bar-action lock and the bottom in a back-action lock, off which the tumbler bounces. This design was widely adopted, appearing in both new guns and as conversions to existing locks. In his third patent, No. 3774 of 30 December 1869, Stanton reverses the location of the projections on the mainspring limbs for bar-action and back-action locks, adding a characteristic curve to the end of the spring. But it was Daniel B. Wesson’s and James H. Bullard’s U.S. patent 198,228 of 18 December 1877, adapted specifically to “revolving fire-arms”, that served as the pattern for numerous subsequent designs.

While the British (e.g. Webley Mk I and its descendants), American (e.g. Colt M1889, S&W M1896, and their descendants), Swiss (e.g. M1872 and its descendants), and French (e.g. Manurhin MR73) rebounding hammer designs rest the face of the hammer on the frame when the trigger is pulled back all the way, allowing the firing pin to protrude from the breech, the German designs realized in the Walther PP and P38 autopistol, the ERMA ER777 revolver, and indeed every Korth revolver produced to date, leave a gap between the face of the hammer and the rear end of the frame-mounted firing pin, relying on the inertia of the hammer to transmit the energy stored in the mainspring to the firing pin, and thence, to the primer. When the hammer is released either in single or double action, the firing pin may fail to travel far enough past the breach to strike the primer. By holding back the trigger after the hammer releases, it should be possible to push the hammer spur further forward to make the firing pin extend past the breach. However, with the hammer strut and mainspring at full extension, the momentum of the falling hammer may not suffice to propel the firing pin all the way forward, resulting in light strikes. Given that the design of the revolver fixes the span of the mainspring compression by cocking the hammer in single and double action alike, the only solution is to increase the energy stored therein by upgrading its spring rate.