WO2025085601A1

WO2025085601A1 - Modular architecture firearm system with roller-delayed blowback

Info

Publication number: WO2025085601A1
Application number: PCT/US2024/051724
Authority: WO
Inventors: Mehmet Metin TOKLUOGLU; Kutlay Kaya
Original assignee: Rots Sterk LLC
Current assignee: Rots Sterk LLC
Priority date: 2023-10-17
Filing date: 2024-10-17
Publication date: 2025-04-24
Anticipated expiration: 2026-04-17

Abstract

A modular firearm system (10) includes an upper receiver assembly (200), a lower receiver assembly (100) configured for attachment to the upper receiver assembly (200), and a roller-delayed blowback bolt mechanism (300) disposed within the upper receiver assembly (200) and configured to interface with the lower receiver assembly (100) to receive a cartridge and eject a spent cartridge case through the upper receiver assembly (100). The roller-delayed blowback bolt mechanism (300) is configured to move rearward within the upper receiver assembly (200) to cause the spent cartridge case to contact an ejector (132) within the lower receiver assembly (100) when pressure resulting from firing the cartridge reaches a predetermined level.

Description

MODULAR ARCHITECTURE FIREARM SYSTEM WITH ROLLER-DELAYED BLOWBACK

FIELD OF THE INVENTION

[0001] The subject matter disclosed herein relates to automatic firearms and, in particular, to an automatic firearm system that combines the benefits of a roller-delayed blowback bolt mechanism with the modular upper and lower receiver architecture of gas-operated firearm systems.

BACKGROUND OF THE INVENTION

[0002] A roller-delayed blowback system is a firearm operating mechanism that has been used in various firearms, particularly in submachine guns such as the Heckler & Koch MP5 and some rifles such as the Heckler & Koch HK33 and G3. The roller-delayed blowback system operates on the principle of delaying the opening of the bolt or breech until the pressure inside the chamber has dropped to a safe level. With respect to this pressure, the spring-loaded bolt locking lever on to the bolt head unlocks. This is achieved through the use of rollers that are pushed outward by the pressure generated during firing. The rollers then engage with recesses in the receiver, preventing the bolt from opening until the pressure has decreased.

[0003] Once the pressure is safe, the rollers allow the bolt to move rearward, ejecting the spent cartridge case and chambering a new round. During firing, when a round is discharged, the bullet travels down the barrel, and the expanding gases push the cartridge case backward. As the cartridge case moves backward, it also pushes the bolt rearward, initially against the resistance of the two rollers. The rollers, which are held in place by their own inertia and a slight angle, begin to move outward along a taper in the barrel extension. This motion delays the rearward movement of the bolt, effectively slowing down the opening of the action.

[0004] Once the rollers have moved a certain distance and overcome the initial resistance, they exit the tapered section and move freely. At this point, the bolt can continue its rearward movement, extracting the spent cartridge case, ejecting it, and chambering a new round from the magazine. When the bolt moves forward again, the rollers are forced back into their original position by a combination of the bolt's angle and the barrel extension's shape. This locks the action in place until the next round is fired.

[0005] In traditional roller-delayed blowback operating system firearms (e.g., the MP5, HK33, G3, etc.), the receiver is a singular component, and all other parts are welded onto it.

[0006] In contrast, gas-operated firearms systems typically use a modular construction, with the parts pinned or otherwise connected to each other. Traditionally, the lower receiver of a gas-operated firearms such as the Colt AR-15, AR-10, M4, M16, Heckler & Koch HK416, HK417, etc., is the part of the firearm that includes the trigger mechanism, magazine well, and pistol grip. The upper receiver of a gas-operated firearm houses and protects the components on the top of the firearm.

[0007] The barrel is where the projectile (bullet) travels through when fired through a firearm. It is securely fixed to the receiver and includes the chamber where the cartridge is seated before firing. A gun barrel has a generally hollow cylindrically shaped barrel with a first end, a second end, an inner surface and an outer surface. The inner surface defines a plurality of internal spiral grooves and the outer surface defines a plurality of external spiral grooves. Traditional roller-delayed blowback operating system firearms have barrel chamber flutes which are longitudinal grooves cut in the chamber that allow propellant gases to surround fired cartridge thereby equalizing external and internal gas pressures, which facilitate extraction or bolt operation in a delayed blow-back firing mechanism.

[0008] In contrast, on gas-operated firearm systems (AR-15, AR-10, M4, M16, HK416, HK417, etc.), the barrel has a gas port drilled on it. The port allows gas produced inside the barrel to escape and to be vented into the gas block where it is used to operate the bolt to eject the spent cartridge.

[0009] The trigger mechanism includes the trigger, hammer, sear, and other components responsible for initiating the firing sequence. When the trigger is pulled, it releases the hammer, which strikes the firing pin or striker, igniting the primer in the cartridge. Traditionally, on firearms that employ the roller-delayed blowback operating mechanism, the trigger mechanism is housed in a grip house that is a separate part of the firearm.

[0010] A roller-delayed blowback mechanism includes several parts, including a bolt head, a bolt carrier, and rollers. The bolt head contains locking rollers that engage with recesses in the barrel extension. The bolt carrier houses the bolt head and reciprocates within the receiver. Traditional roller-delayed blowback mechanisms feature an anti-bounce mechanism that prevents the bolt from bouncing off the barrel's breech surface. Generally, it is a spring-loaded claw mounted on the top of the bolt and referred as bolt locking lever.

[0011] The handguard that is attached to the receiver of a roller-delayed blowback firearm or an upper receiver of a gas-operated firearm is for protecting the end-user from the heat dissipation from the barrel during operation. Another feature of handguards on gas-operated firearm systems is to be a housing for mounting accessories.

[0012] In traditional roller-delayed blowback mechanism firearms, a unique magazine component is typically used with respect to the design of the firearm. Thus, each firearm model has its own type of magazine.

[0013] The above information disclosed in this Background section is only for understanding of the background of the inventive concepts and, therefore, it may contain information that does not constitute prior art.

SUMMARY OF THE INVENTION

[0014] The present disclosure is directed, in a first aspect, to a modular firearm system. The modular firearm system includes an upper receiver, a lower receiver configured for attachment to the upper receiver, and a roller-delayed blowback bolt mechanism disposed within the upper receiver and configured to interface with the lower receiver mechanism to receive a cartridge and eject a spent cartridge case through the upper receiver. The roller-delayed blowback bolt mechanism is configured to move rearward within the upper receiver to cause the spent cartridge case to contact an ejector within the lower receiver when pressure resulting from firing the cartridge reaches a predetermined level.

[0015] In an embodiment of the modular firearm system, the roller-delayed blowback bolt mechanism may include a pair of grooves configured to contact a pair of rails on the upper receiver, and two recoil springs disposed in parallel.

[0016] In another embodiment, the modular firearm system may further include a handguard assembly including a cocking mechanism for the roller-delayed bolt mechanism.

[0017] In a further embodiment of the modular firearm system, the lower receiver may include a magazine well, and a trigger group having a sear and an ejector configured for operation with the roller-delayed bolt mechanism.

[0018] In yet another embodiment of the modular firearm system, the roller-delayed blowback bolt mechanism may include vertical locking components configured to feed cartridges from a gas-blowback type of magazine.

[0019] The present disclosure is also directed, in a second aspect, to a modular roller-delayed blowback firearm. The modular roller-delayed blowback firearm includes a lower receiver assembly having: a monolithic lower receiver having a magazine well, a front pivot pin, and a rear pivot pin; and a trigger pack having an ejector and a sear configured for roller-delayed blowback operation. The modular roller-delayed blowback firearm also includes a barrel and upper receiver assembly including: a barrel having a proximal end and a distal end; a barrel extension disposed at the proximal end of the barrel configured for engaging a cartridge; and an upper receiver having a positioning plate and retainer for engaging a proximal end of the barrel extension and having a lower front hole disposed to engage the front pivot pin, a lower rear hole disposed to engage the rear pivot pin, and a pair of steel rail inserts extending parallel to the barrel. The modular roller-delayed blowback firearm further includes a roller-delayed blowback bolt mechanism assembly including: a bolt head having a pair of rollers; a bolt carrier attached to the bolt head and having a pair of grooves configured to engage the steel rails of the upper receiver; and a pair of recoil spring sub-assemblies attachable to the bolt carrier to be disposed parallel to the grooves. The modular roller-delayed blowback firearm additionally has a handguard assembly having a proximal end configured for attachment to a distal end of the upper receiver, the handguard assembly including: a handguard having a notched charging slot, the handguard configured to surround a portion of the barrel in a spaced relationship; and a cocking assembly configured for engaging the notched charging slot and the bolt carrier.

[0020] In one or more embodiments, at least one of the upper receiver and the handguard may include an accessory attachment rail.

[0021] In an embodiment of the modular roller-delayed blowback firearm, the recoil spring sub-assemblies may include springs and spring rods, and the upper receiver may include a pair of openings configured for passage of the spring rods therethrough.

[0022] In another embodiment of the modular roller-delayed blowback firearm, the roller- delayed blowback bolt mechanism assembly may include vertical locking components.

[0023] In a further embodiment of the modular roller-delayed blowback firearm, the lower receiver assembly may include a bolt catch configured for operation with the roller-delayed blowback bolt mechanism.

[0024] The present disclosure is further directed, in a third aspect, to an assembly for a roller- delayed blowback firearm. The assembly includes: a barrel having a proximal end and a distal end; a barrel extension disposed at the proximal end of the barrel configured for engaging a cartridge; and an upper receiver. The upper receiver has: a positioning plate and retainer for engaging a proximal end of the barrel extension; a lower front hole disposed to engage a front pivot pin of a lower receiver; a lower rear hole disposed to engage a rear pivot pin of the lower receiver; a pair of front openings configured to allow passage of spring rods; and a pair of steel rail inserts extending parallel to the barrel to engage a bolt carrier of a roller-delayed blowback bolt mechanism. [0025] In an embodiment, the assembly may further include the roller-delayed blowback bolt mechanism, the roller-delayed blowback bolt mechanism having: a bolt head having a pair of rollers; the bolt carrier attached to the bolt head and having a pair of grooves configured to engage the steel rails of the upper receiver; a pair of recoil spring sub-assemblies attachable to the bolt carrier to be disposed parallel to the grooves; and a centrally-mounted locking lever pin disposed on a rear of the bolt carrier.

[0026] In another embodiment, the assembly may further include a handguard assembly having a proximal end configured for attachment to a distal end of the upper receiver, the handguard assembly including: a handguard having a notched charging slot, the handguard configured to surround a portion of the barrel in a spaced relationship; and a cocking assembly configured for engaging the notched charging slot and the bolt carrier.

[0027] In one or more embodiments of the assembly, the handguard may include a cocking channel and the cocking assembly may include: a charging handle configured to pass through the notched charging slot; a cocking bearer disposed in the cocking channel and having a distal end configured to connect to the charging handle and a proximal end for engaging the bolt carrier; and a cocking sear disposed adjacent the cocking bearer.

[0028] In a further embodiment, the assembly may also include a lower receiver assembly having: a monolithic lower receiver having a magazine well, the front pivot pin, and the rear pivot pin; and a trigger pack having an ejector configured for discharging spent cartridge cases from the roller-delayed blowback bolt mechanism.

BRIEF DESCRIPTION OF FIGURES

[0029] The features of the disclosure believed to be novel and the elements characteristic of the invention are set forth with particularity in the appended claims. The figures are for illustration purposes only and are not drawn to scale. The disclosure itself, however, both as to organization and method of operation, can best be understood by reference to the description of the preferred embodiment(s) which follows, taken in conjunction with the accompanying drawings in which:

[0030] FIG. 1A is a left-side view of a firearm in accordance with the present disclosure;

[0031] FIG. IB is a right-side view of a firearm in accordance with the present disclosure;

[0032] FIG. 2A is left-side view of a lower receiver in accordance with the present disclosure;

[0033] FIG. 2B is right-side view of a lower receiver in accordance with the present disclosure;

[0034] FIG. 3A is right-side view of an upper receiver and barrel in accordance with the present disclosure;

[0035] FIG. 3B is left-side view of an upper receiver and barrel in accordance with the present disclosure;

[0036] FIG. 3C is front view of an upper receiver and barrel in accordance with the present disclosure;

[0037] FIG. 3D is rear view of an upper receiver and barrel in accordance with the present disclosure;

[0038] FIG. 4A is right-side view of a bolt carrier group assembly in accordance with the present disclosure;

[0039] FIG. 4B is left-side view of a bolt carrier group assembly in accordance with the present disclosure;

[0040] FIG. 4C is rear view of a bolt carrier group assembly in accordance with the present disclosure;

[0041] FIG. 4D is front view of a bolt carrier group assembly in accordance with the present disclosure;

[0042] FIG. 4E is perspective view of a bolt carrier group assembly in accordance with the present disclosure; [0043] FIG. 5 is left-side view of a bolt carrier part in accordance with the present disclosure;

[0044] FIG. 6 is perspective view of a bolt carrier part in accordance with the present disclosure;

[0045] FIG. 7A is perspective view of a bolt locking lever in accordance with the present disclosure;

[0046] FIG. 7B is a perspective view of a bolt locking pin in accordance with the present disclosure;

[0047] FIG. 8A is right-side view of a handguard and cocking handle assembly in accordance with a left-hand version of the present disclosure;

[0048] FIG. 8B is left-side view of a handguard and cocking handle assembly in accordance with a left-hand version of the present disclosure;

[0049] FIG. 8C is right-side view of a handguard and cocking handle assembly in accordance with a right-hand version of the present disclosure;

[0050] FIG. 8D is rear view of a handguard and cocking handle assembly in accordance with a right-hand version of the present disclosure;

[0051] FIG. 8E is front view of a handguard and cocking handle assembly in accordance with a right-hand version of the present disclosure;

[0052] FIG. 8F is a left-side cross-sectional view of a handguard and cocking handle assembly in accordance with a right-hand version of the present disclosure;

[0053] FIG. 9 is a view of a charging handle in accordance with the present disclosure;

[0054] FIG. 10 is a view of a cocking sear in accordance with the present disclosure;

[0055] FIG. 11 is a view of a cocking bearer in accordance with the present disclosure;

[0056] FIG. 12A is a top view of a lower receiver assembly in accordance with the present disclosure; [0057] FIG. 12B is a left-side view of a lower receiver in accordance with the present disclosure;

[0058] FIG. 12C is a right-side view of a lower receiver in accordance with the present disclosure;

[0059] FIG. 13 is an embodiment of a bolt catch in accordance with the present disclosure;

[0060] FIG. 14 is an embodiment of an ejector in accordance with the present disclosure;

[0061] FIG. 15 is an embodiment of a sear in accordance with the present disclosure; and

[0062] FIG. 16 is an embodiment of a positioning plate in accordance with the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

[0063] The embodiments of the present disclosure can comprise, consist of, and consist essentially of the features and/or steps described herein, as well as any of the additional or optional ingredients, components, steps, or limitations described herein or would otherwise be appreciated by one of skill in the art.

[0064] The following discussion omits or only briefly describes conventional features of the disclosed technology that are apparent to those skilled in the art. Reference to a particular embodiment does not limit the scope of the claims attached hereto. Additionally, any examples set forth in this specification are intended to be non-limiting and merely set forth some of the many possible embodiments for the appended claims. Further, particular features described herein can be used in combination with other described features in each of the various possible combinations and permutations. A person of ordinary skill in the art would know how to use the instant invention, in combination with routine experiments, to achieve other outcomes not specifically disclosed in the examples or the embodiments.

[0065] Unless otherwise specifically defined herein, all terms are to be given their broadest possible interpretation including meanings implied from the specification as well as meanings understood by those skilled in the art and/or as defined in dictionaries, treatises, etc. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art in the field of the disclosed technology. It must also be noted that, as used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless otherwise specified, and that the terms "includes" and/or "including," when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. Additionally, methods, equipment, and materials similar or equivalent to those described herein can also be used in the practice or testing of the disclosed technology.

[0066] The devices of the present disclosure may be understood more readily by reference to the following detailed description of the embodiments taken in connection with the accompanying drawing figures, which form a part of this disclosure. It is to be understood that this application is not limited to the specific devices, methods, conditions or parameters described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting. All spatial references, such as, for example, proximal, distal, horizontal, vertical, top, upper, lower, bottom, left and right, are for illustrative purposes only and can be varied within the scope of the disclosure. For example, the references "upper" and "lower" are relative and used only in the context to the other, and are not necessarily "superior" and "inferior."

[0067] It will further be understood that, although the terms "first," "second," "third," and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Thus, "a first element" discussed below could be termed "a second element" or "a third element," and "a second element" and "a third element" may be termed likewise without departing from the teachings herein.

[0068] Various examples of the disclosed technology are provided throughout this disclosure.

The use of these examples is illustrative only, and in no way limits the scope and meaning of the invention or of any exemplified form. Likewise, the invention is not limited to any particular preferred embodiment(s) described herein. Indeed, modifications and variations of the invention may be apparent to those skilled in the art upon reading this specification, and can be made without departing from its spirit and scope. The invention is therefore to be limited only by the terms of the claims, along with the full scope of equivalents to which the claims are entitled.

[0069] The present disclosure is directed to an automatic firearm system and components thereof that combine the benefits of a roller-delayed blowback bolt mechanism with the modular upper and lower receiver architecture of gas-operated firearm systems.

[0070] With reference to FIGS. 1A and IB, an embodiment of a modular automatic firearm system 10 may include an upper receiver assembly 200, a lower receiver assembly 100 configured for attachment to the upper receiver assembly 200, and a roller-delayed blowback bolt mechanism 300 disposed within the upper receiver assembly 200 and configured to interface with the lower receiver assembly 100 to receive a cartridge (not shown) and eject a spent cartridge case through the upper receiver assembly 200. The roller-delayed blowback bolt mechanism 300 is configured to move rearward within the upper receiver assembly 200 to cause the spent cartridge case to contact an ejector 132 within the lower receiver assembly 100 when pressure resulting from firing the cartridge reaches a predetermined level.

[0071] The modular automatic firearm system 10 may be adapted to use standard magazines 150 as used in various gas-operated firearm systems. Similarly, the lower receiver assembly 100 and/or the upper receiver assembly 200 of the modular automatic firearm system 10 may be adapted to include an interface butt plate 260 for mounting various accessories used in various gas-operated firearm systems such as stocks, sliding stocks, or foldable stocks 260, or sling attachments.

[0072] In one or more embodiments, the modular automatic firearm system 10 may include a handguard assembly 400 including a cocking mechanism for the roller-delayed blowback bolt mechanism 300. FIGS. 1A and IB illustrate the modular automatic firearm system 10 in a "right- hand" configuration wherein an operator's right hand grips the handgrip for operation of the trigger so that a left hand would be used to operate the cocking mechanism located on a left side of the handguard assembly 400. For left-hand operation, the modular nature of the automatic firearm system 10 allows the use of a left-handed handguard assembly 400 that includes a cocking mechanism of an opposite side for right hand operation while an operator's left hand is adjacent the trigger, as illustrated in FIGS. 8A and 8B.

[0073] Referring to FIGS. 2A, 2B, and 12A an embodiment of a lower receiver assembly 100 in accordance with the present disclosure is illustrated. As illustrated in FIGS. 2A, 2B, 12B, and 12C, the lower receiver assembly 100 includes a monolithic lower receiver 110 having a magazine well 155, a front pivot pin 120, and a rear pivot pin 122. The front and rear pivot pins 120, 122 may permit the lower receiver 110 to be attached to and removed from the upper receiver assembly 200 without the use of tools via insertion/removal of a pivot pin and a taketown pin in a known manner as used for gas-operated firearms.

[0074] The magazine well 155 may dimensioned to receive standard magazines 150 from gas- operated firearms. The magazine well 155 may also be appropriately angled to permit a roller- delayed blowback bolt mechanism 300 to properly pick up and feed a cartridge from the magazine 150. The lower receiver assembly 100 may also include a magazine release 182 that operates within magazine well 150 to secure magazine 155 upon insertion and release magazine 155 upon activation of magazine release 182 by an operator.

[0075] The lower receiver 110 may be an extruded part (see FIGS. 12B and 12C), such as an aluminum extrusion, and may include symmetrical elements to permit the installation of a bolt catch/release 180 (see, also, FIG. 13), magazine release 182, and/or safety selector 184 in an ambidextrous manner on either side of the lower receiver 110. In other embodiments, the lower receiver 110 may also come in specific right or left-hand versions. The lower receiver 110 may also house a trigger pack 130 and mounts for a trigger guard 186. The trigger pack 130 may use some components from trigger elements available for gas-operated firearms, but should have an ejector 132 (see FIG. 14) and a sear 134 (see FIG. 15) configured for roller-delayed blowback operation with the roller-delayed blowback bolt mechanism 300.

[0076] Indeed, traditional roller-delayed blowback firearm systems do not include such parts as bolt catch/release 180 and sear 134. Furthermore, typical bolt catch/release and sear parts that are present in gas-operated firearm systems are not compatible with any roller-delayed blowback system type ejectors. In this regard, both bolt catch/release 180 and sear 134 of the present disclosure have geometrical and dimensional differences that enable them to be execute their functions like they were in a gas-operated firearm system, and yet in adaptation with the existence of an roller-delayed blowback system ejector 132 in the lower receiver 110

[0077] The lower receiver 110 may include a rear portion 170 for retaining the upper receiver assembly 200 and/or retaining interface butt plate 260. Rear portion 170 may include one or more push buttons 190 to ease in assembly, disassembly, or addition of accessories. The lower receiver 110 may also include a mount for a grip 188 such that lower receiver assembly 100 may use standard interchangeable grips designed for gas-operated firearms.

[0078] With reference to FIGS. 3A, 3B, 3C, and 3D, an embodiment of an upper receiver and barrel assembly 200 is illustrated.

[0079] The upper receiver and barrel assembly 200 includes a barrel 210 having a proximal end and a distal end. The distal end may include a flash suppressor 212, which may, for example, be screwed onto threads located at the distal end of barrel 210. The barrel 210 may be forged and/or machined out of suitable grades of steel, and may include barrel chamber flutes (i.e., longitudinal grooves cut in the chamber) to allow propellant gases to surround the fired cartridge, thereby equalizing external and internal gas pressures to facilitate extraction or bolt operation of the roller-delayed blowback bolt mechanism 300.

[0080] The upper receiver and barrel assembly 200 also includes a barrel extension 220 disposed at the proximal end of the barrel 210. The distal end of the barrel extension 220 is configured with a chamber for engaging a cartridge and may have a lip configured for feeding and extraction of cartridge cases.

[0081] The barrel extension 220 may be thermally connected to a heat sink 222 disposed adjacent thereto. The heat sink 222 may have fins to increase its surface area for heat transfer to the surroundings, and may be dimensioned so as to not interfere with or contact the handguard assembly 400.

[0082] A proximal end of the barrel extension 220 may be connected to an upper receiver 230 with a positioning plate 248 (see FIG. 16) and a retainer 249. The retainer 249 may be formed as a metal locking pin and may be shaped as a prismatic bar-like element. In traditional roller- delayed blowback system firearms, assembly of the barrel to the receiver consists of multiple welding operations. The positioning plate 248 and retainer 249 allow the assembly of upper receiver 230 and barrel extension 220 together without any welding and/or pressing operation, which makes it more efficient and cost-effective for mass production. The proximal end of barrel extension 220 further includes chamber configured to receive a cartridge from the roller- delayed blowback bolt mechanism 300.

[0083] Upper receiver 230 may be formed as an extrusion, such as an aluminum extrusion, and may include additional machined elements. The upper receiver 230 includes the positioning plate 248 for engaging a proximal end of the barrel extension 220. A lower side of the upper receiver 230 includes retainer 249 for attachment to the lower receiver 110. In an embodiment, a tab includes a lower front hole 234 disposed to engage the front pivot pin 120 and a tab with a lower rear hole 236 disposed to engage the rear pivot pin 122. When such attachment means are used, the upper receiver 230 and the lower receiver 110 may be assembled and disassembled without tools.

[0084] As shown in FIG. 3B, the upper receiver 230 includes a dust cover 242 and a separator 246 disposed on one side thereof. In traditional roller-delayed blowback system firearms, these parts and their features have not existed. In the present disclosure, these parts and their functions have been adapted from gas-operated systems for use in the present roller-delayed blowback system. Dust cover 242 prevents dirt, debris, and dust from getting into the firearm's internal operating system. Separator 246 guides the spent cartridge case outside of the firearm mechanism through an ejection port of the upper receiver 230. The separator 246 may be formed through polymer injection molding.

[0085] In one or more embodiments, an left-hand upper receiver 230 may include an ejection port groove on an opposite side of the upper receiver 230, and when used with a left-hand handguard assembly 400 and a different seating groove for extractor 132 on the bolt head 310, may provide for left-hand operation.

[0086] The upper receiver 230 may further include an accessory attachment rail 240 such as a Picatinny rail (MIL-STD-1913) or NATO accessory rail (STANAG 4694), which may be formed integrally with the upper receiver 230. In alternate embodiments, it may be separate and bolted onto the upper receiver 230. Accessories such as lights, scopes, laser sights, etc. may be attached to firearm 10 using the accessory attachment rail 240.

[0087] Upper receiver 230 also includes a pair of steel rail inserts 232 extending parallel to the barrel 210. The steel rail inserts 232 may be fastened to the inner wall of upper receiver 230 via machine screws or any other means, such as a friction fit. The steel rail inserts 232 will typically have lubrication disposed thereon to provide a sliding surface for the roller-delayed blowback bolt mechanism 300 to reciprocate upon.

[0088] As illustrated in FIG. 3C, a front or distal portion of upper receiver includes a pair of openings 238 for passage of spring rods of spring assemblies 330 (see FIGS. 4A-4E) of the roller- delayed blowback bolt mechanism 300 ,and a central opening 239 for passage of cocking bearer 450 (see FIGS. 8A-8F and 11) used to move the roller-delayed blowback bolt mechanism 300, as discussed further below.

[0089] Referring to FIGS. 4A-4E, an embodiment of a roller-delayed blowback bolt mechanism 300 in accordance with the present disclosure is illustrated. [0090] The roller-delayed blowback bolt mechanism 300 includes a bolt head 310 having a pair of rollers 312. The rollers 312 are configured on bolt head 312 such that rollers 312 are pushed outward by the pressure generated during firing. The rollers 312 then engage with recesses in the upper receiver 230, preventing the roller-delayed blowback bolt mechanism 300 from opening until the pressure has decreased. Once the pressure is safe, the rollers 312 allow the roller-delayed blowback bolt mechanism 300 to move rearward, ejecting the spent cartridge case.

[0091] A bolt carrier 320 is attached to the bolt head 310 and includes a pair of parallel grooves 350, one on each side of bolt carrier 320. The grooves 350 are configured to engage the steel rails 232 of the upper receiver 230. The bolt carrier 320 with grooves 350 may be formed in any suitable manner such as forging and/or machining and may be made of a suitable steel.

[0092] A pair of recoil spring sub-assemblies 330 are attachable to the bolt carrier 320 to be disposed parallel to the grooves 350. Each recoil spring sub-assembly 330 includes a spring rod, a coil spring disposed around the spring rod, and a spring retainer at one end of the spring rod, as is generally known in the art of firearms. In use, the spring rods pass through openings 238 of upper receiver 230 and are attached to the bolt carrier 320, such as by a threaded or bayonettype attachment. The springs do not pass through openings 238 and are compressed by the spring retainer when the roller-delayed blowback bolt mechanism 300 moves rearward, and provide a return force to permit the roller-delayed blowback bolt mechanism 300 to pickup and feed a new cartridge when moving forward.

[0093] Referring to FIGS. 4A, 6, 7A, and 7B, a bolt locking lever pin 340 may be mounted centrally on a rear wall of bolt carrier 320. Bolt locking lever pin 340 functions to increase the force applied to the ammunition when the roller-delayed blowback bolt mechanism 300 unlocks. This function of bolt locking lever pin 340 allows the firearm system 10 to generate the maximum bullet speed. In traditional roller-delayed firearm systems, the corresponding part is placed with 35-degree angle to the centerline of the barrel. This angled positioning generates angular momentum forces due its positioning, which causes wear that requires maintenance and eventually replacement of the part in the firearm system. In accordance with the present disclosure, the central location of the bolt locking lever pin 340 reduces the angular forces on the part itself, which improves the longevity of the part as well as the firearm system 10 itself. Additionally, because the angular momentum forces are eliminated, the recoil effect that the operator is exposed during operation is also decreased.

[0094] The bolt locking lever pin 340 may be formed in any suitable manner, such as forging and/or machining, and may be made of any suitable steel. A bolt locking lever 342 may be mounted on one side of the bolt head 310 in a position forward of the roller 312. The bolt locking lever 342 is assembled to the bolt carrier 320. During operation, the pressure generated from the firing action is transferred from the rollers 312 that are in locked position to the bolt head 310. With the initiation of movement of the bolt head 310 through this pressure, the bolt locking lever 342 opens up and initiates the spent cartridge case ejection procedure. The bolt locking lever 342 may be formed in any suitable manner, such as forging and/or machining, and may be made of any suitable steel.

[0095] In one or more embodiments, the bolt head 310 or the bolt carrier 320 may include a pocket with a lid 360 into which Tungsten granules may be inserted to maximize a balance of the cycling of the roller-delayed blowback bolt mechanism 300.

[0096] With reference to FIGS. 8A-8F, 9, 10, and 11 embodiments of a handguard assembly 400 for use with the modular automatic firearm system 10 may include a cocking mechanism for the roller-delayed blowback bolt mechanism 300.

[0097] The handguard assembly 400 includes a handguard 410. Handguard 410 includes a fitting with an attachment screw 412 at a lower proximal end thereof for attachment of the handguard 410 to a lower distal portion of the upper receiver 230. The handguard 410 may be dimensioned to surround the barrel 210, barrel extension 220, and heat sink 222 in a spaced relationship, such that the barrel 210 "floats" within the handguard 410. [0098] Handguard 410 may be formed of extruded aluminum and/or machined, and may include a plurality of openings for allowing passage of cooling air to the barrel 210 and heat sink 222 as well as providing grip for an operator. Handguard 410 may also include an accessory attachment rail 440 on an upper portion thereof, which may be formed integrally or attached thereto. Accessory attachment rail 440 may be configured to continue from accessory attachment rail 240 of upper receiver 230 in a substantially uninterrupted manner when the handguard 410 is installed on upper receiver 230. Handguard 410 may also include M-LOK attachment points on the sides and bottom thereof for additional third-party accessories such as sling attachments.

[0099] Handguard 410 further includes cocking channel 432 disposed in an upper portion and extending parallel to the barrel 210, and a notched charging slot 420 in an upper side portion to permit operation of a cocking assembly using a charging handle 430 that passes through charging slot 420. The cocking assembly includes a cocking bearer 450 disposed in the cocking channel 432 and having a distal end configured to connect to the charging handle 430 and a proximal end for engaging the bolt carrier 320. The cocking assembly also includes a cocking sear 460 disposed adjacent the cocking bearer 450.

[00100] The cocking sear 460 functions as a movement bridge between the charging handle 430 and the bolt mechanism 300. During operation, once the charging handle 430 is pulled, the cocking sear 460 act as a crank and allows the bolt head 310 to unlock within the bolt mechanism 300. This enables the operator to eject the empty cartridge case and/or nonfired ammunition from the chamber of the barrel 210 manually. Furthermore, with this operational function of the cocking sear 460, the bolt mechanism 300 can be pulled back for initial feeding of ammunition to the firearm system 10.

[00101] Accordingly, the roller-delayed blowback bolt mechanism 300 of modular automatic firearm system 10 may be cocked by pulling charging handle 430 rearward ly within charging slot 420. If the operator desires the bolt to remain open, the charging handle 430 may be rotated into the notch of the charging slot 420. [00102] Handguard assemblies 400 may be made in both right-hand and left-hand versions to allow ambidextrous operation of firearm 10.

[00103] In accordance with the present disclosure, a firearm may be provided that has a two-piece architecture, with upper and lower receivers respectively, similar to gas-operated firearms and yet operates with roller-delayed blowback operating mechanism. More particularly, a firearm system in accordance with the present disclosure can manufactured with modern materials, such as aluminum, with modern manufacturing methods, such as being forged or extruded. An additional object of the present disclosure is to merge both functional and operational benefits of roller-delayed blowback and gas-operated platforms in a singular firearm design.

[00104] An additional benefit of the present disclosure is that, with the adoption of upper and lower receiver parts, welding of various parts and components together and/or on to the receiver, as done in traditional roller-delayed blowback mechanism firearms, may be avoided.

[00105] Another advantage of the present disclosure is that, with the adoption of upper and lower receiver parts, and the configuration of the roller-delayed blowback mechanism, assembly and disassembly of the disclosed firearm does not require any special fixtures, tools, or any other industrial level equipment.

[00106] A firearm in accordance with the present disclosure can function with MP5, HK33, and G3 type trigger pack components with the exception of the ejector and sear. An additional benefit of the present firearm is that the design configuration can accept gas operated firearm (AR-15, AR-10, M4, M16, HK416, HK417, etc.) type of trigger pack components as well.

[00107] The present disclosure includes a unique design of an ejector and sear, where it allows the firearm system to eject empty cartridge cases through the upper receiver compatibly with roller delayed blowback firing mechanism. [00108] In accordance with the present disclosure, the disclosed modular firearm can provide higher tolerances, increased precision, and more serviceability and/or repair to a firearm. An additional benefit of the present disclosure is that, with the commonality of consisting a two piece, upper and lower receivers respectively, similar to gas-operated firearms, the end-user may mount and/or attach various accessories, such as grips, handguards, picatinny rails, to the present firearm, which are generally compatible with gas operated firearm systems, but not roller-delayed blowback mechanism firearms.

[00109] A firearm in accordance with the present disclosure may include push buttons and pivot pins similar to gas operated firearm systems (AR-15, AR-10, M4, M16, HK416, HK417, etc.) for ease of assembly and disassembly.

[00110] A firearm in accordance with the present disclosure may include a dust cover mechanism attached to its upper receiver component with compatibly function with a roller- delayed blowback mechanism.

[00111] A firearm in accordance with the present disclosure may include an ambidextrous magazine release, bolt catch, and/or safety selector component, to provide enhanced operational experience to the end-user.

[00112] A firearm in accordance with the present disclosure may include a barrel that can be replaced easily and very quickly. This feature allows a user to change the barrel to obtain advantages such as having the ability to change barrel and overall firearm length, maintenance and operational longevity of the firearm.

[00113] The present disclosure includes a roller delayed-blowback bolt mechanism 300 that differs from traditional mechanisms in order to achieve compatibility with AR-15 or AR-10 type magazines 150 with respect to the caliber. Multiple features on the bolt head 310 and bolt carrier 320 components allows the bolt group to feed the barrel chamber with cartridges from an AR-15 or AR-10 type magazine with respect to the caliber. In order to achieve this compatibility, the present disclosure employs a new locking mechanism in the form of bolt locking lever pin 340 and bolt locking lever 342 with an operational angle that has been adapted to the bolt carrier 320.

[00114] The present roller-delayed blowback bolt mechanism also differs from traditional mechanisms by using vertical locking components rather than having locking levers, which allows the present inventions' roller delayed blowback mechanism to feed cartridges from an AR-15 or AR-10 type magazine with respect to the caliber.

[00115] The present roller-delayed blowback bolt mechanism further differs from traditional mechanisms by having two recoil springs. The advantage of these two recoil springs is to be able to have the bolt locking lever to be at the center of the bolt group. An additional benefit of the present invention is to reduce the recoil effect of higher-pressure caliber firearms.

[00116] A firearm in accordance with the present disclosure may include a handguard having a modular design, where the cocking mechanism of the roller-delayed blowback mechanism can be executed within the handguard system. More particularly, the present disclosure includes a handguard design with the features necessary, i.e., channels and grooves, to charge the cocking handle of the present firearm, so that the bolt group can be charged through the upper receiver.

[00117] In accordance with the present disclosure, a barrel extension may have particular grooves so as to allow a cartridge to slide through barrel extension after being extracted from the magazine by the roller delayed bolt mechanism into the chamber. The present disclosure includes a predetermined angle for the magazine well of the lower receiver to position the cartridges in the AR-15 or AR-10 compatible magazines with respect to the caliber, so that the roller-delayed blowback bolt mechanism can feed the cartridge into the barrel chamber, through the barrel extension and its modified lip.

[00118] While the present disclosure has been particularly described, in conjunction with specific preferred embodiments, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. It is therefore contemplated that the appended claims will embrace any such alternatives, modifications and variations as falling within the true scope and spirit of the present disclosure.

Claims

CLAIMS What is claimed is:

1. A modular firearm system, comprising: an upper receiver; a lower receiver configured for attachment to the upper receiver; and a roller-delayed blowback bolt mechanism disposed within the upper receiver and configured to interface with the lower receiver mechanism to receive a cartridge and eject a spent cartridge case through the upper receiver, wherein the roller-delayed blowback bolt mechanism is configured to move rearward within the upper receiver to cause the spent cartridge case to contact an ejector within the lower receiver when pressure resulting from firing the cartridge reaches a predetermined level.

2. The modular firearm system of claim 1, wherein the roller-delayed blowback bolt mechanism includes: a pair of grooves configured to contact a pair of rails on the upper receiver; and two recoil springs disposed in parallel.

3. The modular firearm system of claim 1, further comprising a handguard assembly including a cocking mechanism for the roller-delayed bolt mechanism.

4. The modular firearm system of claim 1, wherein the lower receiver includes: a magazine well; and a trigger group having a sear and an ejector configured for operation with the roller- delayed bolt mechanism.

5. The modular firearm system of claim 1, wherein the roller-delayed blowback bolt mechanism includes vertical locking components configured to feed cartridges from a gasblowback type of magazine.

6. A modular roller-delayed blowback firearm, comprising: a lower receiver assembly including: a monolithic lower receiver having a magazine well, a front pivot pin, and a rear pivot pin; and a trigger pack having an ejector and a sear configured for roller-delayed blowback operation; a barrel and upper receiver assembly including: a barrel having a proximal end and a distal end; a barrel extension disposed at the proximal end of the barrel configured for engaging a cartridge; and an upper receiver having a positioning plate and a retainer for engaging a proximal end of the barrel extension and having a lower front hole disposed to engage the front pivot pin, a lower rear hole disposed to engage the rear pivot pin, and a pair of steel rail inserts extending parallel to the barrel; a roller-delayed blowback bolt mechanism assembly including: a bolt head having a pair of rollers; a bolt carrier attached to the bolt head and having a pair of grooves configured to engage the steel rails of the upper receiver; and a pair of recoil spring sub-assemblies attachable to the bolt carrier to be disposed parallel to the grooves; and a handguard assembly having a proximal end configured for attachment to a distal end of the upper receiver, the handguard assembly including: a handguard having a notched charging slot, the handguard configured to surround a portion of the barrel in a spaced relationship; and a cocking assembly configured for engaging the notched charging slot and the bolt carrier.

7. The modular roller-delayed blowback firearm of claim 6, wherein at least one of the upper receiver and the handguard includes an accessory attachment rail.

8. The modular roller-delayed blowback firearm of claim 6, wherein recoil spring subassemblies include springs and spring rods, and the upper receiver includes a pair of openings configured for passage of the spring rods therethrough.

9. The modular roller-delayed blowback firearm of claim 6, wherein the roller-delayed blowback bolt mechanism assembly includes vertical locking components.

10. The modular roller-delayed blowback firearm of claim 6, wherein the lower receiver assembly includes a bolt catch configured for operation with the roller-delayed blowback bolt mechanism.

11. An assembly for a roller-delayed blowback firearm, comprising: a barrel having a proximal end and a distal end; a barrel extension disposed at the proximal end of the barrel configured for engaging a cartridge; and an upper receiver having: a positioning plate and a retainer for engaging a proximal end of the barrel extension, a lower front hole disposed to engage a front pivot pin of a lower receiver; a lower rear hole disposed to engage a rear pivot pin of the lower receiver; a pair of front openings configured to allow passage of spring rods; and a pair of steel rail inserts extending parallel to the barrel to engage a bolt carrier of a roller-delayed blowback bolt mechanism.

12. The assembly of claim 11, further comprising the roller-delayed blowback bolt mechanism, the roller-delayed blowback bolt mechanism including: a bolt head having a pair of rollers; the bolt carrier attached to the bolt head and having a pair of grooves configured to engage the steel rails of the upper receiver; a pair of recoil spring sub-assemblies attachable to the bolt carrier to be disposed parallel to the grooves; and a centrally-mounted locking lever pin disposed on a rear of the bolt carrier.

13. The assembly of claim 12, further comprising a handguard assembly having a proximal end configured for attachment to a distal end of the upper receiver, the handguard assembly including: a handguard having a notched charging slot, the handguard configured to surround a portion of the barrel in a spaced relationship; and a cocking assembly configured for engaging the notched charging slot and the bolt carrier.

14. The assembly of claim 13, wherein the handguard includes a cocking channel and the cocking assembly includes: a charging handle configured to pass through the notched charging slot; a cocking bearer disposed in the cocking channel and having a distal end configured to connect to the charging handle and a proximal end for engaging the bolt carrier; and a cocking sear disposed adjacent the cocking bearer.

15. The assembly of claim 12, further comprising a lower receiver assembly including: a monolithic lower receiver having a magazine well, the front pivot pin, and the rear pivot pin; and a trigger pack having an ejector configured for discharging spent cartridge cases from the roller-delayed blowback bolt mechanism.