Firearms – Firing mechanism – Rearward sliding breech bolt
Reexamination Certificate
1998-08-03
2001-03-27
Johnson, Stephen M. (Department: 3641)
Firearms
Firing mechanism
Rearward sliding breech bolt
C042S070080, C042S022000
Reexamination Certificate
active
06205694
ABSTRACT:
BACKGROUND—FIELD OF INVENTION
This invention relates to pistols, specifically to externally adjustable coil hammer mainspring assemblies for pistols.
BACKGROUND—DESCRIPTION OF PRIOR ART
A review of prior art hammer mainspring design indicates three basic types of hammer mainsprings. The first type, the flat or leaf spring design, is found in many rifles and pistols, both old and new. The desire to make these mainsprings externally adjustable was known as early as 1905 as evidenced by Mason U.S. Pat. No. 846,591 which provided an external screw adjustment to the leaf spring of an automatic rifle. A more recent (1982) example of an adjustable leafspring in a pistol is shown in Karlsen U.S. Pat. No. 4,361,072.
The second mainspring type is relatively rare and entails a spiral hammerspring which is a rolled up piece of flat steel which resembles a clock mainspring. An adjustable version of this mainspring type is found in Brinkerhoff U.S. Pat. No. 1,711,874.
The third mainspring type found in firearms is the helical coil mainspring. These mainsprings have been utilized in both rifles and pistols for quite some time. An early (1914) example of a rifle with a non-externally adjustable helical coil mainspring can be found in Swebilius U.S. Pat. No. 1,103,228.
A review of foreign and domestic patents and firearms literature revealed a total of two 1950's era starter pistols and no rifles with externally adjustable helical coil mainspring assemblies. All other coil hammer mainspring rifles and pistols are adjustable only by disassembling the gun. The first, covered under German patentanmeldung E 9365 XI/72b to Eberwein, is a starter pistol with a short helical coil mainspring which is adjustable via a slotted threaded plug in the butt end of the pistol housing. The second, shown in German patentschrift 830,465 to Gerstenberger, is also a starter pistol with a helical coil mainspring which is adjustable via a slotted threaded rod which passes through and meshes with a threaded nut which is affixed to the inside of the butt end of the pistol housing.
The prior art relating to the coil hammer mainspring has a number of disadvantages. For example, the coil hammer mainspring may experience fatigue and its tension may weaken over time, affecting hammerfall strike force which can interfere with a firearms ability to properly detonate a cartridge. Trigger-pull may also be affected by this weakened mainspring. Also, the pistol operator may not like the trigger-pull and/or hammerfall force currently existing in their pistol and may desire to change it to suit their needs. Arguably, the worst case scenario is a broken coil hammer mainspring which renders the firearm inoperable. Thus, with the exception of two 1950's era starter pistols, the prior art requires the gun owner to visit a gunsmith who will be required to disassemble the firearm and change-out the coil hammer mainspring to adjust coil hammer mainspring tension. This process is, of course, time consuming, costly, and quite unacceptable in a situation where coil hammer mainspring adjustment is needed now, not later.
The two 1950's era starter pistols have design characteristics which make the capability they possess, that of external coil hammer mainspring adjustment, not transferable to many of the pistols in service today. This occurs because neither of these pistols incorporated design features which allow the external drive mechanism to bypass internal or external obstructing gun parts. These design deficiencies prohibit incorporation of external coil hammer mainspring adjustment on many widely popular pistols, including but not limited to, the Colt 1911, the Beretta 92, the Smith and Wesson model 659, the Browning 9 mm Hipower, and all Para-Ordinance models.
Another disadvantage to the design of the two 1950's era starter pistols is that neither can be adjusted without tools. If the pistol user is out in the field without the right tool, external adjustment is of no help.
SUMMARY OF THE INVENTION
It is therefore a primary object of the present invention to provide a firearm, such as a pistol, with a helical coil hammer mainspring external adjustment, thereby permitting trigger-pull and hammerfall strike force to be adjusted in the field. An additional object is to permit the firearm owner, in many cases, to make the firearm function with a broken coil hammer mainspring. Other objects and advantages of the present invention are:
(a) to allow externally adjustable coil hammer mainspring housing assemblies to be incorporated in pistols which have internal design features which would otherwise prohibit the inclusion of external adjustment given the prior art;
(b) to provide trigger-pull and hammerfall force adjustment in the field without the use of tools;
(c) to allow externally adjustable coil hammer mainspring assemblies to be incorporated into pistols which have external design features which would otherwise prohibit the inclusion of external adjustment given the prior art. A good example of this is the Beretta model 92 which has a lanyard on the butt end of the pistol which is aligned with the axis of the coil mainspring; and
(d) To provide a unique safety device which disables the pistol.
REFERENCES:
patent: 1141256 (1915-06-01), Nelson
patent: 1344884 (1920-06-01), Guyot
patent: 1712411 (1929-05-01), Walther
patent: 2691232 (1954-10-01), Hoopes
patent: 2945316 (1960-07-01), Mulno
patent: 4967502 (1990-11-01), Vernon
patent: 5361525 (1994-11-01), Bowes
patent: 120493 (1930-12-01), None
patent: 495194 (1976-02-01), None
Alchemy Arms Company; Spectve Performance, Technology, and Safety, 2 pages No Date.
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