Patent Abstract:
An improved semiautomatic firearm is provided comprising as assembly which reduces the effort of cocking the firearm or loading a first cartridge. A spring tube contains an inner recoil spring which is employed only during cycling of the firearm when firing. For initial cocking purposes, the inner recoil spring is bypassed in favor of a lighter outer spring which is selectively engaged by the user. When the inner recoil spring is engaged, both inner and outer springs are employed without adversely affecting the recoil dynamics of the firearm.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This nonprovisional patent application claims priority under 35 U.S.C. §119 to U.S. Provisional Application Ser. No. 61/307,204, filed on Feb. 23, 2010. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
     Not applicable. 
     INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON COMPACT DISC 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to semiautomatic firearms, and particularly to such firearms having a lighter cocking action and less felt recoil. 
     2. Description of Related Art 
     Semi-automatic pistols commonly include a slide normally biased in a forward position on the frame, but movable rearwardly of the frame by the recoil produced by a fired cartridge. A recoil spring is coupled to the slide and is compressed as the slide moves rearwardly of the frame. As the slide clears the magazine below and reaches the slide stop, the recoil spring urges the slide back to its original position and loads another cartridge from the magazine into the chamber. Such pistols are initially loaded by inserting a magazine of cartridges into the butt of the pistol, and then manually drawing the slide back against the action of the recoil spring, and then releasing it, to load the first cartridge into the firing chamber and to cock the hammer. After each firing of a cartridge, the pistol thereafter utilizes the recoil produced by the firing of that cartridge to cock the pistol for the next cartridge, and introduce a new cartridge into the chamber. 
     Manually pulling back the slide to load the first cartridge requires a substantial manual effort, typically in excess of 5-10 pounds of force. Such a large manual force may be difficult to apply for certain persons without the required strength to operate the pistol, particularly by some women or older persons. Moreover, this large manual force to initially load the pistol may limit the strength of the recoil spring that may be used, and thereby the recoil action absorbed by the recoil spring. 
     Over the years, a number of devices have been developed in connection with semiautomatic firearms to either reduce the cocking effort or felt recoil when firing, including U.S. Pat. No. 4,173,169 to Yates; U.S. Pat. No. 4,201,113 to Seecamp; U.S. Pat. No. 4,344,352 to Yates; and U.S. Pat. No. 5,955,696 to Meller. While these devices may be suited to their specific applications, they do not provide the benefits achievable through use of the present invention. 
     What is generally needed is a semiautomatic firearm which enables easier or lighter cocking action than is available in current semiautomatic firearms. The lighter cocking action should permit easier loading of a first round from the magazine to the chamber, but should also permit the recoil spring to resume normal function during firing and subsequent loading of rounds from the magazine. Finally, the improved mechanisms described herein should be implemented in a manner that avoids or minimizes additional weight or volume to the resulting firearm. 
     SUMMARY OF THE INVENTION 
     A semiautomatic firearm with reduced cocking action and reduced recoil is provided, comprising a firing chamber, a barrel, a frame, a slide movable with respect to the barrel and the frame between battery and full recoil positions, means for sequentially ejecting a spent cartridge and loading a fresh cartridge during each recoil cycle, and a firing mechanism for firing the cartridge when the slide is in battery, wherein the improvement comprises an assembly for enabling only a single lighter spring to cock the pistol and/or load a first cartridge. 
     In a preferred embodiment, the assembly comprises a spring tube having a rear end and a front end, and including an outer surface and a pair of diametrically opposed longitudinal slots extending from the front end to the rear end, and wherein the spring tube is slidably disposed within an opening in the slide. An inner spring resides within the spring tube, wherein the inner spring includes a first spring constant. An outer spring resides around the outer surface of the spring tube, wherein the outer spring includes a second spring constant and an annular cap connected to the front end of the outer spring. 
     Preferably, a locking device is disposed within the front end of the inner spring, and having opposing tabs slidably engaged within the slots of the spring tube and with the opening of the slide, and wherein the opposing tabs are biased against the front end of the slots by the annular cap of the outer spring. 
     A spring stop is operatively connected to the rear end of the spring tube and engaged with the barrel, wherein the spring stop includes a rod residing coaxially within the inner spring. 
     An anti-rotation spring is operatively attached between the spring tube and the spring stop, wherein the anti-rotation spring is adapted to permit partial and biased rotation of the spring tube and the locking device relative to the spring stop between a first rotational position and a second rotational position. 
     The opening in the slide includes opposing recesses adapted to permit slidable passage of the opposing tabs through the opposing recesses, and to allow compression of only the outer spring, when the locking device and the spring tube are in the second rotational position for loading a first cartridge. 
     Also, the opposing tabs are engaged by the slide, and both the inner spring and the outer spring are allowed to compress, when the locking device and the spring tube are in the first rotational position for firing the first cartridge and subsequent cartridges. 
     Preferably, the spring stop includes a detent engaged with a first end of the anti-rotation spring, and wherein the spring stop includes a clamp engaged with the detent and with the spring tube. 
     In a preferred embodiment, the longitudinal slots are closed at the front end of the spring tube and open at the rear end of the spring tube. 
     The firearm further includes means for resetting the locking device from the second rotational position back to the first rotational position. 
     Preferably, each of the opposing recesses of the opening in the slide include a ramp slidably engageable with one of the opposing tabs of the locking device; and a locking surface adjacent to the ramp adapted to receive and lock the opposing tab in the first rotational position. 
     Also more preferably, the slide includes an unlocking device adapted to move the opposing tabs of the locking device from the locked first rotational position to the second rotational position. 
     More preferably, the unlocking device includes a grip member slidably disposed along the slide; a connecting member extending from the grip member, wherein the connecting member includes a plunger ramp; and a plunger slidably disposed within a plunger slot on the slide, wherein the plunger is operatively engaged between the plunger ramp and one of the opposing tabs of the locking device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements. 
         FIG. 1  shows an exploded perspective view of selected components in accordance with one embodiment of the present invention. 
         FIG. 2  shows an assembled view of the embodiment of  FIG. 1 . 
         FIG. 3  shows an assembly view of the invention in combination with the barrel and slide of a semiautomatic firearm with the assembly in a pre-cocked configuration. 
         FIG. 4  shows an assembly view of the invention during a cocking action and loading of a first cartridge, wherein only the outer spring is compressed, because the locking device and spring tube are in a first rotational position. 
         FIG. 5  shows an assembly view of the invention during the firing of subsequent cartridges, wherein both the outer spring and the inner spring are compressed, because the locking device and the spring tube are in a second rotational position. 
         FIGS. 5A-5C  show detailed views of invention at different stages of the assembly. 
         FIGS. 6A and 6B  show partial sectional side views of the front of the firearm depicting the operation of the locking device and unlocking device relative to the slide. 
         FIG. 7  shows a perspective view of one embodiment of a modified front portion of the slide used in connection with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Before the subject invention is further described, it is to be understood that the invention is not limited to the particular embodiments of the invention described below, as variations of the particular embodiments may be made and still fall within the scope of the appended claims. It is also to be understood that the terminology employed is for the purpose of describing particular embodiments, and is not intended to be limiting. Instead, the scope of the present invention will be established by the appended claims. 
     In this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural reference unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. 
     Turning now to  FIGS. 1 and 2 , the invention relates to improvements to a semiautomatic firearm  1  to provide reduced cocking effort and easier loading of a first cartridge (or “round”), as well as reduced felt recoil. All semiautomatic pistols  1  include a firing chamber  2 , a barrel  3 , a frame, a slide  5  movable with respect to the barrel  3  and the frame between battery and full recoil positions, means for sequentially ejecting a spent cartridge and loading a fresh cartridge during each recoil cycle, and a firing mechanism for firing the cartridge when the slide  5  is in battery.  FIGS. 3-5  are shown with a partially assembled view of the firearm to illustrate the internal components described herein. It should be appreciated that the grip and frame of the firearm should remain essentially unchanged from a conventional semiautomatic pistol, except for differences specific to designs from various manufacturers. 
     With reference to the exploded view of  FIG. 1 , in a preferred embodiment, the improved firearm  1  comprises a spring tube  6  having a rear end  7  and a front end  8 , and including an outer surface and a pair of diametrically opposed longitudinal slots  9  extending from the front end  8  to the rear end  7 , and wherein the spring tube  6  is slidably disposed within an opening  10  in the slide  5  (best shown in  FIGS. 4 and 5 ). 
     An inner spring  11  resides within the spring tube  6 , wherein the inner spring  11  includes a first spring constant. In a more preferred embodiment, the inner spring  11  is the main recoil spring, although such arrangement is not necessarily required by the present invention. 
     An outer spring  12  resides around the outer surface of the spring tube  6 , wherein the outer spring  12  includes a second spring constant. As mentioned above, the inner spring  11  may often be the main recoil spring. If that is the case, then the second spring constant of the outer spring  12  would be less than the first spring constant of the inner spring  11 . In other words, the outer spring  12  would be much lighter, or easier to compress, than the inner spring  11 . The outer spring  12  includes an annular cap  13  connected to the front end of the outer spring  12 . 
     A locking device  14  is disposed within the front end of the inner spring  11  (best shown in  FIGS. 2 and 4 ), and includes opposing tabs  15  slidably engaged within the slots  9  of the spring tube  6  when fully assembled. The opposing tabs  15  are biased against the front end of the slots  9  by inner spring  11 , because the inner spring  11  should be slightly compressed during assembly. 
     A spring stop assembly  16  is operatively connected to the rear end of the spring tube  6  and engaged with the barrel  3 , wherein the spring stop assembly  16  includes a base member  21  having a curved portion  22  to engage the barrel  3 , and a rod  17  residing coaxially within the inner spring  11 . The spring stop assembly  16  is shown best in  FIGS. 5A-5C , which figures illustrate the sequential addition of other components for clarity, as will be further explained below. The base member  21  further includes an annular concave surface  23  that provides a seat for the inner spring  11  and ensures concentricity between the inner spring  11  and rod  17 . The base member  21  also includes an anti-rotation spring mounting surface  24  that is coaxial with rod  17 . 
     With further reference to  FIG. 5A , an anti-rotation spring  18  roughly in the shape of a partial or open band is operatively attached around the surface  24 . The anti-rotation spring  18  includes a first flange  25  and a second flange  26 . When the anti-rotation spring  18  is installed, the second flange  26  rests partially on a boss  27  protruding from the face of the base member  21 . Thus, an angular gap A is present when the anti-rotation spring  18  is uncompressed. As will be appreciated, the inside diameter of the anti-rotation spring  18  should be slightly larger than the diameter of the surface  24  so that full compression of the spring  18  between the first and second flanges  25 ,  26  may be accomplished unimpeded. 
     With reference to  FIG. 5B , the inner spring  11  is shown inserted within the spring tube  6 , and the spring tube  6  and inner spring  11  are mounted on the rod  17 . As described above, the locking device  14  is also positioned on the opposite end of the inner spring  11  and is biased against the ends of slots  9 , as shown in  FIGS. 2 and 4 . To secure the components for assembly, the spring tube  6  includes a circumferential flange  28  that rests against the face of base member  21 . A U-shaped clamp  20  having a C-shaped cross section is mounted onto the base member  21  to firmly retain the spring tube  6  to the base member  21 . Although the clamp  20  may be secured in various ways, the means in  FIG. 5B  illustrates a notch in the clamp  20  that snaps onto the boss  27 . In the preferred embodiment, the spring tube  6  further includes a cutout portion  30  at the rear end of one of the slots  9 . The cutout portion  30  should be sized such that the bottom edge  31  of the slot  9  fits snugly under the boss  27 , and such that the upper edge  32  of the cutout portion  30  rests on the first flange  25  of the anti-rotation spring  18 . When assembled, the anti-rotation spring  18  should be slightly in compression to avoid rattling and ensure a secure fit. From this arrangement, it can be understood that the anti-rotation spring  18  is compressed when the locking device  14  and the spring tube  6  are rotated relative to the base member  21  through angle A between a first rotational position (shown in  FIGS. 5B and 5C ) and a second rotational position. The maximum rotation is achieved when the first and second flanges  25 ,  26  are contacting each other. 
     With reference to  FIG. 5C , the outer spring  12  is shown added to the assembly, such that the rear end of the outer spring  12  rests against the clamp  20 . The front end of the outer spring  12  and the annular cap  13  are slightly biased against the opposing tabs  15  of the locking device  14 , as shown in  FIG. 2 . 
     Referring now to  FIGS. 3-5 , and  FIGS. 6A ,  6 B, and  7 , in a preferred embodiment, the opening  10  in the slide  5  includes opposing recesses  19  adapted to permit slidable passage of the opposing tabs  15  through the opposing recesses  19 , and to permit axial compression of only the outer spring  12 , after the locking device  14  and the spring tube  6  are rotated from the first rotational position. Each of the opposing recesses  19  of the opening  10  in the slide  5  include a ramp  35  slidably engageable with one of the opposing tabs  15  of the locking device  14 . Each recess  19  also includes a locking surface  36  adjacent to the ramp  35  adapted to receive and lock the opposing tab  15  in the second rotational position. More preferably, the locking surface  36  has an adjacent concave surface  37 , such that when the opposing tab  15  is seated on the locking surface  36 , inadvertent dislodgement of the opposing tab  15  from the first rotational position is avoided. As can be appreciated, the internal features of the opposing recesses  19  just described for the left-most recess  19  of  FIG. 7  are inverted for the right-most recess  19 . Specifically, when the opposing tabs  15  are urged against the ramps  35 , the locking device  14  and the spring tube  6  are caused to rotate clockwise (from the view in  FIG. 7 ). Thus, when the locking device  14  is fully seated in the first rotational position on locking surfaces  36 , pulling back the slide  5  will cause both inner spring  11  and outer spring  12  to be compressed. Such configuration represents the arrangement desired for normal firing and cycling of the firearm, because the inner spring  11  (typically the main recoil spring) is employed. 
     However, when the user desires to manually load a new cartridge into the firearm, the locking device  14  needs to be disengaged from the slide  5  so that only the outer spring  12  is employed. To accomplish this function, the slide  5  includes an unlocking device  40  adapted to move the opposing tabs  15  of the locking device  14  from the locked first rotational position to a second rotational position. 
     In a preferred embodiment, and with reference to  FIGS. 3-5 ,  6 A,  6 B, and  7 , the unlocking device  40  includes a grip member slidably disposed along the slide  5 , such as on a slidable rail. The grip member  41  moves relative to the slide  5  through a short distance D when pulled back, until it reaches a stop member  42  on the slide  5 . A connecting member  43  extends from the grip member  41  toward the front of the slide  5 , wherein the connecting member  43  includes a plunger ramp  44  with an inclined surface positioned above the locking device  14 . A plunger rod  45  is slidably disposed within a plunger slot  46  on the slide  5 , such that the upper end of the plunger rod  45  is in slidable contact with the plunger ramp  44 , and such that the lower end of the plunger rod  45  is immediately above the opposing tab  15  of the locking device  14 . The plunger rod  45  and plunger slot  46  may include means to spring-load the plunger rod  45  or otherwise limit its slidable range within the plunger slot  46  so as not to interfere with the return of the opposing tabs  15  when the slide  5  is closed. 
     Thus, starting from the position shown in  FIG. 6A , when the grip member  41  is pulled back, the plunger ramp  44  causes the plunger rod  45  to move downward within the plunger slot  46  in proportion to the distance D against the resistance of the opposing tab  15  of the locking device  14 . At the maximum position of the grip member  41 , the plunger rod  45  has rotated the opposing tabs  15  away from their respective locking surfaces  36 . Such action takes place against the resistance of the anti-rotation spring  18  described above. Further pulling of the grip member  41  will cause the entire slide  5  to move backward, while the opposing tabs  15  pass through their respective recesses  19 . After the opposing tabs pass through the recesses  19 , the locking device  14  and spring tube  6  resume their normal horizontal position by the expansion of the anti-rotation spring  18 . Concurrently, the slide  5  can be fully retracted against the force of the outer spring  12  alone until the trigger mechanism is cocked and the slide  5  reaches it maximum travel. 
     After the slide  5  is fully retracted against the outer spring  12  only, it can be released to strip a cartridge from the magazine and place the cartridge into the firing chamber  2 . Return of the slide  5  toward its closed position then causes the opposing tabs  15  of the locking device  14  to contact the ramps  35  within the recesses  19 . Prior to the slide  5  reaching its full forward position, the opposing tabs  15  slide along the ramps  35  against the force of the anti-rotation spring  18  until they snap back onto the locking surfaces  36 . Simultaneously with this action, the plunger ramp  44  and plunger rod  45  are returned to their original positions shown in  FIG. 6B . 
     Now that the firearm has been manually loaded, it can be fired in the normal manner. When the cartridge is fired, the slide  5  now moves backward with the opposing tabs  15  of the locking device  14  locked in the first rotational position. Therefore, cycling of the action and subsequent stripping of the cartridges from the magazine occur against the resistance of both the inner spring  11  and the outer spring  12 . Advantageously, this condition also helps to reduce felt recoil during firing. 
     The unlocking device assembly  40 , and particularly the connecting member  43 , plunger ramp  44 , and plunger  45  are preferably enclosed within a cover on the slide  5  so that such components are fully protected. Also, with respect to the choice of springs and spring constants for the inner spring  1  and the outer spring  12 , persons of ordinary skill in the art of firearms design will appreciate that specific spring selection will vary, taking into consideration the dynamics of the particular firearm, ammunition type, and other factors. 
     Notably, the spring constant for the outer spring  12  only needs to be sufficient to prevent inadvertent or undesired movement of the slide  5  relative to the frame during handling of the firearm Likewise, the spring constant of the outer spring  12  should not be too strong as to adversely affect the dynamics of the recoil and loading action of the firearm. 
     It should be emphasized that the invention is not limited to pistols, but may also be applied with suitable modification to rifles, shotguns, and similar semiautomatic firearms where it may be desirable to reduce the effort required to cock the firearm and/or load a first cartridge. The invention can also be implemented in a manner that does not appreciably increase the weight or size of the firearm. 
     All references cited in this specification are herein incorporated by reference as though each reference was specifically and individually indicated to be incorporated by reference. The citation of any reference is for its disclosure prior to the filing date and should not be construed as an admission that the present invention is not entitled to antedate such reference by virtue of prior invention. 
     It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of methods differing from the type described above. Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention set forth in the appended claims. The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.

Technology Classification (CPC): 5