Patent Publication Number: US-10775121-B2

Title: Firearm mechanism

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Patent Application No. 62/526,355, filed Jun. 29, 2017, and the benefit of U.S. Patent Application No. 62/620,459, filed Jan. 22, 2018, the entire content of which are hereby incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to automatic machine guns and fire control mechanisms. 
     Automatic firearms generally have high firing rates. For example, M4 and M16 machine guns can fire 700-900 or more rounds per minute. While a high firing rate has certain benefits, there can be drawbacks such as decreased accuracy and increased ammunition consumption. 
     There remains a need for firearm mechanisms having variable rates of fire. 
     There remains a need for novel firearm mechanisms, as well as firearm mechanisms that can be retrofit into existing machine guns to reduce the cycle rate. 
     All US patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety. 
     Without limiting the scope of the invention a brief summary of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below. 
     BRIEF SUMMARY OF THE INVENTION 
     In some embodiments, a firearm mechanism comprises a bolt carrier comprising a rear cavity, a buffer sleeve and a buffer. The buffer sleeve defines an internal cavity. The buffer sleeve is arranged to contact the bolt carrier and is arranged to contact a buffer spring. The buffer is arranged to move with respect to the bolt carrier and the buffer sleeve. The buffer is at least partially oriented in the buffer sleeve. A length of the buffer is greater than a length of the internal cavity. 
     In some embodiments, a firearm mechanism comprises a hammer, an auto-sear, a bolt carrier, a buffer and a buffer sleeve. The bolt carrier comprises a body and a striker moveable with respect to the body between a first position and a second position. The striker is biased to the first position by a biasing mechanism. The striker does not contact the auto-sear in the first position. The striker contacts the auto-sear in the second position and is arranged to operate the auto-sear in the second position. The buffer sleeve is arranged to contact the bolt carrier. The buffer sleeve surrounds the buffer. The buffer is arranged to contact the striker. A length of the buffer is greater than a length of the buffer sleeve. 
     In some embodiments, a firearm comprises a lower receiver, a bolt carrier, a buffer sleeve and a buffer. The lower receiver is arranged to support a hammer and an auto-sear. The bolt carrier comprises a body and a striker moveable with respect to the body between a first position and a second position. The buffer sleeve is arranged to contact the bolt carrier and to contact a buffer spring. The buffer sleeve defines an internal cavity and comprises open ends. The buffer is oriented in the internal cavity and extends through the buffer sleeve. The buffer is arranged to contact the striker and move the striker to the second position. 
     These and other embodiments which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages and objectives obtained by its use, reference can be made to the drawings which form a further part hereof and the accompanying descriptive matter, in which there are illustrated and described various embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A detailed description of the invention is hereafter described with specific reference being made to the drawings. 
         FIG. 1  shows an exploded view of an embodiment of a firearm mechanism. 
         FIG. 2  shows a cross-sectional view of a portion of a firearm comprising an embodiment of a firearm mechanism. 
         FIGS. 3-8  show the operation of an embodiment of a firearm mechanism during a firing sequence. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While this invention may be embodied in many different forms, there are described in detail herein specific embodiments of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. 
     For the purposes of this disclosure, like reference numerals in the figures shall refer to like features unless otherwise indicated. 
       FIGS. 1 and 2  show an embodiment of a firearm mechanism  10 . 
     In some embodiments, the parts of the firearm mechanism  10  are suitable for use in standard M4 and M16 firearms as drop-in replacement parts, without requiring any change to other parts of the firearm. Reference to an M4 and/or M16 herein is intended to include various M16 rifle models and M4 rifle models and analogues thereof. 
     In some embodiments, when the firearm mechanism  10  is used in an M4, the resulting modified firearm will have a slower firing rate than the standard military specification M4. 
     In some embodiments, a firearm mechanism  10  comprises a bolt carrier  30 , a striker  42  and a buffer mechanism  50 . In some embodiments, the striker  42  is carried by the bolt carrier  30 . In some embodiments, the striker  42  is moveable with respect to the bolt carrier  30 . In some embodiments, the buffer mechanism  50  is arranged to contact and move the striker  42 , and the striker  42  is arranged to cause a firearm to fire. In some embodiments, the striker  42  is arranged to operate an auto-sear of a firearm. 
     In some embodiments, the bolt carrier  30  and buffer mechanism  50  are suitable for use as a replacement for a mil-spec M4 bolt carrier and buffer. In some embodiments, the bolt carrier  30  is constructed and arranged to be used with a mil-spec M4 bolt. In some embodiments, the buffer mechanism  50  is constructed and arranged to be used with a mil-spec buffer spring. 
     In some embodiments, the buffer mechanism  50  comprises a buffer  51  and a buffer sleeve  53 . Desirably, the buffer  51  is moveable with respect to the buffer sleeve  53 . In some embodiments, the buffer sleeve  53  defines a cavity  52  and the buffer  51  is oriented in the cavity  52 . In some embodiments, the buffer sleeve  53  comprises a tubular shape having open front and rear ends. In some embodiments, the buffer sleeve  53  comprises a flange  57  arranged to contact a buffer spring (not illustrated), and the buffer sleeve  53  can be biased by the buffer spring in a manner similar to the way the buffer spring would bias a mil-spec buffer. 
     In some embodiments, the buffer  51  comprises a reciprocating member that is arranged to cause firing of a firearm. In some embodiments, the buffer  51  is constructed and arranged to impact other portions of a firearm. In some embodiments, a first end of the buffer  51  comprises a bumper  68 . In some embodiments, a second end of the buffer  51  comprises a bumper  58 . The bumpers  58 ,  68  can be made from any suitable materials and are desirably elastically deformable under the loading experienced during a firing cycle. In some embodiments, the bumpers  58 ,  68  comprise rubber or urethane. In some embodiments, the bumpers  58 ,  68  are attached to the buffer  51  with respective pins  59 ,  69 . 
     In some embodiments, the buffer  51  is generally free to move with respect to the bolt carrier  30  and with respect to the buffer sleeve  53 . 
     In some embodiments, a magnet  76  is provided. Magnetic forces provided by the magnet  76  can be used to bias the buffer  51  and change travel characteristics of the buffer  51  during shooting. 
       FIG. 2  shows an embodiment of a firearm mechanism  10  positioned with respect to an embodiment of a lower receiver  12 . In some embodiments, the lower receiver  12  comprises a standard military specification M4 or M16 lower receiver. In some embodiments, a lower receiver  12  comprises a hammer  14  and an auto-sear  16 . In some embodiments, the hammer  14  comprises a sear  18  arranged to contact the sear of a finger trigger (not illustrated). In some embodiments, the hammer  14  and auto-sear  16  comprise standard military specification parts. 
     In some embodiments, the striker  42  is moveable with respect to the bolt carrier  30  between first and second positions. In some embodiments, the striker  42  is biased to the first position by a biasing mechanism  60 . In some embodiments, when the striker  42  is in its second position and the bolt carrier  30  is properly oriented with respect to the lower receiver  12 , the striker  42  will operate the auto-sear  16  and fire a round. 
     In some embodiments, the bolt carrier  30  comprises a cavity  32 . In some embodiments, the cavity  32  is open to the rear end  38  of the bolt carrier  30 . In some embodiments, the cavity  32  of the bolt carrier  30  is aligned with the cavity  52  of the buffer sleeve  53 . In some embodiments, a portion of the buffer  51  is oriented in the cavity  32  of the bolt carrier  30  during a portion of a firing cycle. In some embodiments, the buffer  51  is arranged to travel along the length of the cavity  32  of the bolt carrier  30  and along the length of the cavity  52  of the buffer sleeve  53 . 
     In some embodiments, the rear end  38  of the bolt carrier  30  and the front end  54  of the buffer sleeve  53  are arranged to engage one another and self-align. In some embodiments, the front end  54  of the buffer sleeve  53  comprises an inclined surface, peak or frustoconical surface  56  arranged to engage a complimentary shaped declined surface, valley or inverse frustoconical surface of the rear end  38  of the bolt carrier  30 . The complimentary shaped ends  38 ,  54  desirably encourage the bolt carrier  30  and buffer sleeve  53  to align such that a central axis of the cavity  32  of the bolt carrier  30  is coaxial with a central axis of the cavity  52  of the buffer sleeve  53 . 
     In some embodiments, the rear end  38  of the bolt carrier  30  is chamfered. In some embodiments, the front end  52  of the buffer  50  is chamfered. Chamfers can help the buffer  51  to pass smoothly across the transition between the bolt carrier cavity  32  and the buffer cavity  52 . 
     In some embodiments, the striker  42  is positioned at an end of the bolt carrier cavity  32 , and the buffer  51  is arranged to contact the striker  42 . Desirably, the buffer  51  can impact the striker  42  and move the striker  42  to its second position with respect to the bolt carrier  30 . 
     In some embodiments, the bolt carrier  30  comprises a cavity  34  and a slot  35  arranged to support the striker  42 . In some embodiments, the striker  42  is positioned in the slot  35 . In some embodiments, a striker pin  46  is received in the cavity  34  and arranged to engage the striker  42 . In some embodiments, an engaging portion  47  of the striker pin  46  is received in an aperture  43  in the striker  42 . 
     In some embodiments, the biasing mechanism  60  comprises a coil spring  62  extending around the striker pin  46 . In some embodiments, the striker pin  46  comprises a flange  48  arranged to engage the biasing mechanism  60 . In some embodiments, the biasing mechanism  60  and striker pin  46  can be installed in the cavity  34 , the biasing mechanism  60  can be compressed, and the striker  42  installed in the slot  35 , wherein the engaging portion  47  of the striker pin  46  can engage the striker  42 . The biasing mechanism  60  and striker pin  46  can bias the striker  42  against a flange  36  of the bolt carrier  30 . In some embodiments, the striker  42  abuts the flange  36  when the striker  42  is in the first position with respect to the bolt carrier  30 . 
     In some embodiments, the buffer  51  comprises a flange  55  constructed and arranged to receive force applied by the buffer sleeve  53 . In some embodiments, the buffer sleeve  53  comprises a flange  74  constructed and arranged to apply force to the buffer  51 . In some embodiments, the flange  74  extends into the cavity  52  of the buffer sleeve  53 . In some embodiments, a bumper  75  is positioned between the impacting portions of the buffer  51  and the buffer sleeve  53 , for example being positioned between the flanges  55 ,  74 . 
       FIG. 3  illustrates an embodiment of a firearm mechanism  10  at a point in time after a first round has been fired. The bolt carrier  30  and buffer mechanism  50  are traveling in the rearward direction  79 , for example under the force of expanding gasses from the first round being applied to the bolt carrier  30 . In some embodiments, the bolt carrier  30  contacts and biases the buffer sleeve  53  in the rearward direction  79 . In some embodiments, the buffer  51  bottoms out against the striker  42  and moves in the rearward direction  79  along with the bolt carrier  30 . 
     In some embodiments, the buffer  51  is longer than the combined lengths of the bolt carrier cavity  32  and the buffer sleeve cavity  52 . In some embodiments, the buffer  51  extends from the striker plate  42  of the buffer  30 , through the bolt carrier cavity  32  and the buffer sleeve cavity  52 , and extends out of the rear end of the buffer sleeve  53 . 
     Referring to  FIG. 4 , the bolt carrier  30  and buffer mechanism  50  move rearward and in some embodiments, move into a receiver extension tube  18 .  FIG. 4  shows the buffer  51  in its rearmost position. In some embodiments, the rear bumper  58  contacts the back wall of the receiver extension tube  18 , stopping travel of the buffer  51  and in some embodiments, stopping travel of the bolt carrier  30 . 
     In some embodiments, a magnet  76  is provided to apply magnetic forces to various components of the firearm mechanism  10 . In some embodiments, a magnet  76  is provided at the rear of the receiver extension tube  18 . In some embodiments, a magnet  76  comprises a ring defining a central aperture, and a portion of the buffer  51  can be oriented in the central aperture during certain times of a firing operation. In some embodiments, the buffer spring  20  contacts the magnet  76 . 
     In some embodiments, the buffer spring  20  has become compressed and biases the buffer sleeve  53  in a forward direction  78 . In some embodiments, the buffer sleeve  53  contacts the bolt carrier  30 , and the buffer sleeve  53  and the bolt carrier  30  move in the forward direction. 
     In some embodiments, the buffer  51  will remain in its rearward position, for example under the force of inertia and/or under force provided by a magnet  76 , as the buffer sleeve  53  and bolt carrier  30  move with respect to the buffer  51 . 
       FIG. 5  shows the buffer sleeve  53  and bolt carrier  30  displaced from their respective positions in  FIG. 4 . In some embodiments, the buffer  51  remains positioned near the rear of the receiver extension tube  18 . In some embodiments, the magnet  76  helps to retain the buffer  51  in a temporary position near the rear of the receiver extension tube  18 . 
     In  FIG. 6 , the buffer sleeve  53  and bolt carrier  30  have moved farther in the forward direction  78 , and the buffer sleeve  53  is positioned to apply force to the buffer  51 . For example, the flange  74  of the buffer sleeve  53  can transfer force to the flange  55  of the buffer  51 , and forward momentum can transfer from the buffer sleeve  53  to the buffer  51 . The buffer  51  begins to travel in the forward direction  78 . 
       FIG. 7  shows the bolt carrier  30  and buffer sleeve  53  reaching their forward positions with respect to the lower receiver  12  and stop traveling.  FIG. 7  represents a time when a mil-spec M16 generally fires a second round; however, the firearm mechanism  10  does not yet fire. Due to positioning of the bolt carrier  30 , the striker  42  is positioned near the auto-sear  16 . The striker  42  remains biased to its first position with respect to the bolt carrier  30  by the biasing mechanism  60 . The buffer  51  continues to travel in the forward direction  78  and will eventually hit the striker  42 . 
       FIG. 8  shows the buffer  51  impacting the striker  42  and moving the striker  42  to its second position with respect to the bolt carrier  30 . In the second position, the striker  42  can contact and operate the auto-sear  16 , releasing the hammer  14  and firing another round. 
     A firearm comprising a firearm mechanism  10  as disclosed herein can fire more slowly in a fully automatic firing mode than a traditional version of the firearm. The travel of the buffer  51  provides a time delay in the cycling rate. 
     Specifics of the components of the firearm mechanism  10  can be adjusted to provide different adjustments in cycle rate. 
     In some embodiments, the buffer  51  comprises a weight  67 . In some embodiments, the weight  67  comprises a material that is denser than the material used for the buffer  51 . In some embodiments, the weight  67  is provided in a forward cavity and arranged to contact the front bumper  68 . The weight  67  can have any suitable size and shape, and can be made from any suitable material. 
     In some embodiments, the buffer  51  comprises one or more weight reduction cavities. As shown in  FIG. 8 , the buffer  51  includes a rear cavity  65  that is largely hollow. 
     In some embodiments, the weight(s)  67  help deliver energy to the striker  42 . 
     The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this field of art. All these alternatives and variations are intended to be included within the scope of the claims where the term “comprising” means “including, but not limited to.” Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims. 
     Further, the particular features presented in the dependent claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having any other possible combination of the features of the dependent claims. For instance, for purposes of claim publication, any dependent claim which follows should be taken as alternatively written in a multiple dependent form from all prior claims which possess all antecedents referenced in such dependent claim if such multiple dependent format is an accepted format within the jurisdiction (e.g. each claim depending directly from claim  1  should be alternatively taken as depending from all previous claims). In jurisdictions where multiple dependent claim formats are restricted, the following dependent claims should each be also taken as alternatively written in each singly dependent claim format which creates a dependency from a prior antecedent-possessing claim other than the specific claim listed in such dependent claim below. 
     This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.