US20140331535A1

US20140331535A1 - Lower receiver for a firearm

Info

Publication number: US20140331535A1
Application number: US13/975,376
Authority: US
Inventors: Jeffrey A. Robinson; Jeremy A. Robinson; Justin F. Robinson; Rock T. Adams
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-05-13
Filing date: 2013-08-26
Publication date: 2014-11-13

Abstract

A lower receiver for a modular firearm can include a first receiver portion that is removably attachable to a second receiver portion to form the lower receiver. An inner surface of the first receiver portion and an inner surface of the second receiver portion can together define a magazine cavity that is configured to receive a magazine. The lower receiver can be disassembled to provide easy access to inner regions of the lower receiver for cleaning, maintaining, or inspecting the modular firearm.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Patent Application No. 61/822,436, filed May 13, 2013, which is hereby incorporated by reference in its entirety.

FIELD

The present application relates to components for modular firearms. More specifically, the present application relates to lower receivers for modular firearms.

BACKGROUND

Certain firearms, such as the Colt AR-15 and clones of the same, employ modular designs that allow a user to easily repair, replace, or upgrade components, such as an upper and lower receiver. Modular firearms also permit the user to install a variety of accessories, such as aftermarket sights, vertical forward grips, lighting systems, night vision devices, laser-targeting devices, muzzle brakes, and sound suppressors. Due to their flexibility, modular firearms are popular among gun enthusiasts who enjoy building, maintaining, and modifying firearms.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of a lower receiver for a firearm;

FIG. 2 is a front perspective view of a first receiver portion of a lower receiver;

FIG. 3 is a front perspective view of a second receiver portion of a lower receiver;

FIG. 4 is a rear perspective view of a lower receiver;

FIG. 5 is a rear perspective view of a first receiver portion of a lower receiver;

FIG. 6 is a rear perspective view of a first receiver portion of a lower receiver;

FIG. 7 is a front perspective view of a lower receiver;

FIG. 8 is a rear perspective view of a lower receiver;

FIG. 9 is a left side view of a lower receiver;

FIG. 10 is a right side view of a lower receiver;

FIG. 11 is a rear view of a lower receiver;

FIG. 12 is a front view of a lower receiver;

FIG. 13 is a top view of a lower receiver;

FIG. 14 is a bottom view of a lower receiver;

FIG. 15 is a front perspective view of a left side portion of a lower receiver;

FIG. 16 is a rear perspective view of a left side portion of a lower receiver;

FIG. 17 is a front perspective view of a right side portion of a lower receiver;

FIG. 18 is a rear perspective view of a right side portion of a lower receiver;

FIG. 19 is a partially assembled firearm; and

FIG. 20 is an assembly view of a lower receiver for a firearm.

DETAILED DESCRIPTION

A partially assembled AR-15 is shown in FIG. 19. A lower receiver 7 is attached to a stock assembly 6, and an upper receiver 8 is attached to a barrel assembly 5. A magazine 1 is shown withdrawn from a magazine cavity in the lower receiver 7. A sling 2, configured to attach to the barrel assembly 5 and stock assembly 6 via attachment points, is shown detached from the firearm. A bolt carrier assembly 3 and charging handle assembly 4 are also show detached from the firearm.
Prior art lower receivers for modular firearms, such as the lower receiver shown in FIGS. 19 and 20, are formed as a single piece, often through a forging or casting process. Although these prior art lower receivers are relatively inexpensive to manufacture, they are also difficult to clean and do not permit access to various firearm sub-assemblies housed within the receiver.
By contrast, the lower receiver described herein has a two-part construction that provides access to all internal surfaces of the lower receiver when the two parts are disassembled, thereby making it easy to clean. Although more costly and time-consuming to manufacture than a one-piece lower receiver, the two-piece lower receiver has many advantages beyond ease of cleaning, including providing access to various firearm sub-assemblies within the receiver, including the trigger and hammer assemblies. This configuration allows a user to inspect and maintain various sub-assemblies without needing to fully disassemble the firearm. For instance, a user can apply lubricant, such as oil or grease, to moving parts of various sub-assemblies without fully disassembling the firearm, which can save time and simplify the process of maintaining the firearm. A two-piece configuration enables precision machining of internal surfaces of each piece. As a result, intricate openings can be formed in the receiver, such as openings for the trigger and hammer assemblies, and these intricate openings can improve operation of the firearm. Machining can also enable weight reduction by allowing unnecessary material to be removed from internal surfaces of the lower receiver.
A lower receiver 100 can be configured to attach to an upper receiver to form a modular firearm. The lower receiver 100 can include a first receiver portion 200 and a second receiver portion 300. The second receiver portion 300 can be configured to mate with the first receiver portion 200 along a mating surface. In one example, the mating surface can be located along a vertical plane that bisects the lower receiver 100 from a front side surface 170 to a rear side surface 430. Various mating surfaces 350 on the second receiver portion 300 are shown in FIG. 3, and various mating surfaces 550 on the first receiver portion 200 are shown in FIG. 5.
In one example, the first and second receiver portions (200, 300) can be machined from aluminum. Alternately, the first and second receiver portions (200, 300) can be made from any other suitable material, including but not limited to steel, titanium, polymer, carbon fiber, and magnesium, and by any suitable manufacturing process, including but not limited to casting, forging, 3D printing, and injection molding.
The first and second receiver portions (200, 300) can be attached to each other with a plurality of fasteners. In one example, the plurality of fasteners can be inserted through fastener holes 405 located on the second receiver portion 300 of the lower receiver 100, as shown in FIG. 4. The fastener holes can be countersunk to permit the heads of the plurality of fasteners to be recessed into the fastener holes to prevent the fasteners from interfering with a user's grip on the lower receiver 100.
The first receiver portion 200 can have an inner surface 1410, and the second receiver portion 300 can have an inner surface 1415, as shown in FIGS. 3, 5, and 14. Together, the inner surfaces (1410, 1415) of the first and second receiver portions (200, 300) can form a magazine cavity 1405 that is configured to receive a magazine, which can contain ammunition. The magazine cavity 1405 can be deeper near a front side surface 170 of the lower receiver 100 than near the trigger guard 705. The magazine cavity 1405 can have a magazine opening located along a bottom side surface of the lower receiver 100, and the magazine opening can be defined by a surface 1420 that slopes downward toward a front side surface of the lower receiver, as shown in FIG. 7.
The front side surface 170 of the lower receiver 100 can include adequate surface area for inclusion of a plurality of finger recesses 155 that can significantly improve ergonomics of the lower receiver 100 over the prior art lower receivers 7 shown in FIGS. 19-20. In one example shown in FIG. 1, the lower receiver 100 can include four finger recesses 155 on a front side surface of the lower receiver. The lower receiver 100 can include a plurality of finger recesses 160 located along a side surface of the first receiver portion 200, as shown in FIGS. 1 and 2. The lower receiver 100 can include a plurality of finger recesses 420 located along a side surface of the second receiver portion 300, as shown in FIG. 4. In one example, the finger recesses (160, 420) located along side surfaces of the lower receiver can have a scalloped shape, as shown in FIGS. 1 and 4. The plurality of finger recesses (e.g. 155, 160, 42) can allow a user to grip the firearm better than prior art lower receivers 7. For instance, the lower receiver 100 shown in FIG. 1 provides dedicated recesses that allow for secure placement of four fingers, whereas prior art lower receivers 7 do not.
The lower receiver 100 can include a first opening 105 located along a top side surface 180, as shown in FIG. 1. The first opening 105 can be configured to receive, for example, a trigger assembly, a hammer assembly, and a selector assembly. In addition, the lower receiver 100 can be configured to receive a magazine catch assembly, a bolt catch assembly, and a pistol grip assembly.
The magazine catch assembly can include, for example, a magazine catch 33, a magazine catch spring 20, and a magazine button 19, as shown in FIG. 20. The magazine catch assembly can be installed by following a series of steps. First, the magazine catch 33 can be installed into an opening 110 on the first receiver portion 200 of the receiver 100. Second, the magazine spring 20 can be installed over a threaded portion of magazine catch 33 through an opening 310 on the second receiver portion 300 of receiver 100. Next, the magazine button 19 can be screwed onto the threaded portion of the magazine catch 33. Last, the magazine button 19 can be depressed inward toward the receiver 100 to allow the magazine catch 33 to be further threaded until the magazine catch is flush with an outer surface of the second receiver portion 300 of the receiver 100 when the magazine button is not depressed.
During assembly, the receiver 100 can be configured to receive a pistol grip assembly, which can include a pistol grip 44, pistol grip screw 45, and pistol grip lock washer 46, as shown in FIG. 20. The pistol grip 44 can be attached to the receiver 100 by inserting the pistol grip screw 45 through the pistol grip lock washer 46 and pistol grip and into a fastener hole 305 in the lower receiver, which is shown in FIGS. 3 and 5. The fastener hole 305 can be positioned along the mating surface of the first and second receiver portions (200, 300).
In one example, shown in FIGS. 7-18, the receiver 100 can include an integrated trigger guard 705. In another example, shown in FIGS. 1-6, the receiver 100 can be configured to receive an aftermarket trigger guard assembly, such as a MAGPUL trigger guard assembly. As shown in FIG. 20, a trigger guard assembly can include a trigger guard 16 and a trigger guard pin 30 and can be installed by following a series of steps. First, a detent on a front portion of the trigger guard can be depressed to permit the detent to engage an opening 315 in the receiver 100. Next, a rear portion of the trigger guard 16 can be attached to the receiver 100 by installing a trigger guard pin 30 through an opening 410 in the receiver and through an opening in the rear portion of the trigger guard. The trigger guard pin 30 can be installed using a mallet initially and finished with a punch.
The bolt catch assembly can include, for example, a bolt catch 35, bolt catch plunger 42, bolt catch spring 43, and bolt catch pin 34, as shown in FIG. 20. The receiver 100 can include a front bolt catch protrusion 425 and rear bolt catch protrusion 420 extending from the right portion 300 of the receiver, as shown in FIG. 4. The front and rear bolt catch protrusions (425, 420) can include holes (not shown) that permit the bolt catch pin 34 to be installed through the bolt catch protrusions. During assembly, the bolt catch pin 34 can be partially installed into the hole in the rear bolt catch protrusion 420. For instance, the bolt catch pin 34 can be partially installed in the hole in the rear bolt catch protrusion 420 by driving the bolt catch pin 34 in a direction toward the front bolt catch protrusion 425. Next, the bolt catch spring 43 can be inserted into a hole 505 in the right portion 300 of the receiver 100, shown in FIG. 5, and then the bolt catch plunger 42 can be inserted into the same hole 505. Last, the bolt catch 35 can be installed into a bolt catch opening 415 located between the front and rear bolt catch protrusions (425, 420), and then the bolt catch pin 34 can be fully installed by being driven through a hole in the bolt catch 35 and through the hole in the front bolt catch protrusion 425.
The pivot pin assembly can include a pivot pin 18, pivot pin detent 32, and pivot pin detent spring 31, as shown in FIG. 20. The left portion 200 of the receiver 100 can include a raised portion 120. Although not shown in FIG. 1, the raised portion 120 can include a hole extending into the raised portion from an end surface 125 of the raised portion. The pivot pin detent spring 31 can be inserted into the hole 47 in the raised portion 120 and then the pivot pin detent 32 can be installed into the same hole. The pivot pin detent 32 can then be depressed using, for example, a razor blade to provide sufficient clearance between the pivot pin detent and the pivot pin 18 to permit the pivot pin to be installed through the holes 115 in the receiver 100.
The trigger assembly can include a trigger 15, trigger pin 26, trigger spring 17, disconnect 29, and disconnect spring 28, as shown in FIG. 20. The trigger assembly can be inserted into the first opening 105 in the receiver 100. During installation, the trigger spring 17 can be installed onto an outer surface of the trigger 15, and the disconnect spring 28 can be installed inside the trigger 15. Next, the disconnect 29 can be installed onto the trigger 15 and over the disconnect spring 28. The trigger 15 can then be inserted into the first opening 105 in the receiver 100, and then the trigger pin 26 can be installed through a hole 130 in the receiver.
The hammer assembly can include a hammer 39, hammer spring 40, and hammer retaining pin 27, as shown in FIG. 20. The hammer spring 40 can be installed onto the hammer 39. The hammer 39 can then be lowered into the first opening 105 in the receiver 100, and the hammer retaining pin 27 can then be installed through the hole 135 in the receiver.
As shown in FIG. 20, the selector assembly can include a safety selector 41, which is a mechanism that prevents accidental discharge of the firearm. The safety selector 41 can be installed into a hole 140 in the receiver 100 when the hammer 39 is cocked back. Once installed, the safety selector 41 allows the user to switch between safe and semi-automatic modes.
The pistol grip assembly can include a selector detent 22, selector detent spring 21, pistol grip 44, pistol grip screw 45, and lock washer 46. During installation, the pistol grip 44 can be attached to the receiver by installing the pistol grip screw 45 through the lock washer 46 and then through the pistol grip and into a hole 305 in the receiver 100.
The receiver 100 can also include a buffer retainer 25 and a hole 145 for a takedown pin 24. In one example, the receiver 100 can include an opening to receive a takedown pin detent spring 38 and a takedown pin detent 37 configured to engage a buffer tube.
In one example, a lower receiver for a modular firearm can include a first receiver portion and a second receiver portion, where the second receiver portion is configured to mate with the first receiver portion along a mating surface. An inner surface of the first receiver portion and an inner surface of the second receiver portion together can define a magazine cavity configured to receive a magazine. The mating surface is located along a vertical plane that bisects the lower receiver from a front side surface to a rear side surface. The magazine cavity can include a magazine opening along a bottom side surface of the lower receiver, and the magazine opening can be defined by a surface that slopes downward toward a front side surface of the lower receiver. The lower receiver can include a plurality of finger recesses located on a front side surface of the lower receiver, and, in one example, the plurality of finger recesses can include four finger recesses. The lower receiver can include a plurality of finger recesses located on a side surface of the first receiver portion. Similarly, the lower receiver can include a plurality of finger recesses located on a side surface of the second receiver portion. The lower receiver can include a first opening along a top side surface of the lower receiver and a first hole extending from a left side surface to a right side surface of the lower receiver, where the first opening is configured to receive a trigger assembly, and where the first hole is configured to receive a pin to secure the trigger assembly within the first opening of the lower receiver. The lower receiver can include an integrated trigger guard, where the first receiver portion includes a first portion of the integrated trigger guard, and where the second receiver portion comprises a second portion of the integrated trigger guard.
The first receiver portion 200 may also be referred to as a left side portion of the lower receiver for a modular firearm, and can be configured to mate with a right side portion to form a lower receiver for a modular firearm. Similarly, the second receiver portion 300 may also be referred to as a right side portion of the lower receiver for a modular firearm, and can be configured to mate with a left side portion to form a lower receiver for a modular firearm.
During manufacturing of the lower receiver, a variety of manufacturing steps can be performed to the convert a piece of material, such as a piece of 7075 aluminum alloy, into a finished lower receiver. For instance, front and rear pivot pin holes can be drilled, magazine catch slots can be cut, a rear portion of the receiver can be drilled and threaded to accept a buffer tube, a buffer-retainer hole can be drilled, a pistol grip mounting area can be faced off and threaded, a magazine well (i.e. cavity) can be completed, a trigger-guard mounting pin hole can be machined, a receiver end-plate area can be machined, a selector lever hole can be drilled, a trigger pin hole can be drilled, a hammer pin hole can be drilled, a fire-control cavity can be machined, and a plurality of holed can be machined and threaded to permit the first and second receiver portions to be secured together with fasteners.
The Gun Control Act of 1968 (GCA), 18 U.S.C. 921(a)(3) defines the term “firearm” as follows: “. . . (A) any weapon (including a starter gun) which will or is designed to or may readily be converted to expel a projectile by the action of an explosive; (B) the frame or receiver of any such weapon; (C) any firearm muffler or firearm silencer; or (D) any destructive device.” Additionally, 27 CRF 478.11 defines “firearm frame or receiver” as being “that part of a firearm which provides housing for the hammer, bolt or breechblock, and firing mechanism, and which is usually threaded at its forward portion to receive the barrel.” The Firearms Technology Branch of the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) may be responsible for determining whether a new product classifies as a “firearm” or “firearm frame or receiver.”
A product that is deemed a “firearm” or “firearm frame or receiver,” as defined in federal statutes, is subject to certain federal restrictions under the GCA. For example, interstate sales of firearms between certain parties are prohibited. Also, certain serial number marking and record keeping requirements are imposed on manufacturers of firearms and firearm frames and receivers. In some instances, it can be desirable to manufacture a product that is not classified as a “firearm” or “firearm frame or receiver.” In certain instances, a two-piece lower receiver, as described herein, may not be classified as a “firearm” or “firearm frame or receiver.” In one example, the two-piece lower receiver may not contain housings for the hammer, bolt, or firing mechanism and may lack a threaded portion to receive the barrel. This can be accomplished by not completing certain manufacturing steps that would be required to complete the lower receiver. For example, the housings for the hammer, bolt, or firing mechanism may not be machined into the receiver and the receiver may not be threaded to receive the barrel. Consequently, the two-piece lower receiver can remain in an unfinished state to avoid being classified as a “firearm” or “firearm frame or receiver” and can then be sold in interstate commerce without being subject to certain restrictions associated with the GCA. For instance, the unfinished lower receiver can be sold in interstate commerce to a licensed manufacturer who can then finish machining the lower receiver and comply with all GCA requirements, including marking the receiver with a serial number and recording the serial number of the receiver.
In one method, the two-piece lower receiver can be shipped via two separate shipments to avoid being classified as a “firearm” or “firearm frame or receiver.” A first shipment can include a first receiver portion, and a second shipment can include a second receiver portion configured to mate with the first receiver portion along a mating surface. The first and second shipments can be shipped on the same day. Alternately, the first and second shipments can be shipped on different days. For example, the second shipment can be shipped 1-2 days, 1-3 days, 1-7 days, or more than one day after the first shipment. By staggering the timing of the first and second shipments, the shipper can ensure that the first and second shipments are never at the same location (e.g. warehouse, aircraft, or delivery truck) at the same time during transit, which can enhance safety and may comply with the GCA, since neither the first receiver portion or the second receiver portion may alone be classified as a “firearm” or a “firearm frame or receiver.” In one example, the first receiver portion and the second receiver portion may include housings for the hammer, bolt, and firing mechanism and the first and second receiver portions may be threaded to receive the barrel. In another example, the first receiver portion and the second receiver portion may not include housings for the hammer, bolt, or firing mechanism and the first and second receiver portions may not be threaded to receive the barrel. In yet another example, one of the first or second receiver portions may include housings for the hammer, bolt, and firing mechanism.
A method for shipping a firearm receiver can include shipping a first portion of the firearm receiver in a first shipment. The method can also include shipping a second portion of the firearm receiver in a second shipment after the first shipment has been shipped. The second shipment can be delayed by a predetermined time to avoid overlap of the first and second shipments during transit. For example, the second shipment can be delayed by one or more days to avoid overlap of the shipments during transit. The first and second lower receiver portions can be completely machined and ready for assembly and use. Alternately, key features, such as openings for a hammer assembly, bolt catch assembly, or trigger assembly, may not be machined into the first and second portions, thereby rendering the portions unusable as a firearm absent subsequent machining steps. In one method, subsequent machining steps can be performed by a third-party that receives the first and second shipments. In one example, the third-party can be a manufacturer having a Federal Firearms License (FFL).
In one example, a modular firearm can include a lower receiver, and the lower receiver can include a first receiver portion and a second receiver portion configured to mate with the first receiver portion along a mating surface, where an inner surface of the first receiver portion and an inner surface of the second receiver portion define a magazine cavity configured to receive a magazine. The mating surface can be located along a vertical plane that bisects the lower receiver from a front side surface to a rear side surface. The magazine cavity can include a magazine opening along a bottom side surface of the lower receiver, and the magazine opening can be defined by a surface that slopes downward toward a front side surface of the lower receiver. The modular firearm can include a plurality of finger recesses located on a front side surface of the lower receiver. In one instance, the plurality of finger recesses can include four finger recesses. The modular firearm can include a plurality of finger recesses located on a side surface of the first receiver portion. The modular firearm can include a plurality of finger recesses located on a side surface of the second receiver portion. The modular firearm can include a first opening along a top side surface of the lower receiver and a first hole extending from a left side surface to a right side surface of the lower receiver, where the first opening can be configured to receive a trigger assembly, and where the first hole can be configured to receive a pin to secure the trigger assembly within the first opening of the lower receiver. The modular firearm can include an integrated trigger guard, where the first receiver portion includes a first portion of the integrated trigger guard, and where the second receiver portion includes a second portion of the integrated trigger guard.
Although this application focuses on a two-part configuration for a lower receiver for a firearm, this is not limiting. Other portions of the firearm can be produced as a two-piece configuration. For instance, an upper receiver for a firearm can be made using a two-piece configuration. In particular, an upper receiver for a modular firearm can include a first receiver portion and a second receiver portion, and the second receiver portion can be configured to mate with the first receiver portion along a mating surface.
The concepts described herein and defined by the enumerated claims may be better understood by referring to the description, which should be read in conjunction with the accompanying figures. The descriptions of certain embodiments are set out to enable one to build and use implementations of the invention, and are not intended to limit the enumerated claims, but rather to serve as particular examples thereof. Those skilled in the art should appreciate that they may readily use the conception and specific embodiments disclosed as a basis for modifying or designing other methods and systems for carrying out the same purposes. Those skilled in the art should also realize that such equivalent assemblies do not depart from the spirit and scope of the invention in its broadest form.

Claims

1. A lower receiver for a modular firearm, the lower receiver comprising:

a first receiver portion; and

a second receiver portion configured to mate with the first receiver portion along a mating surface, wherein an inner surface of the first receiver portion and an inner surface of the second receiver portion together define a magazine cavity configured to receive a magazine.

2. The lower receiver of claim 1, wherein the mating surface is located along a vertical plane that bisects the lower receiver from a front side surface to a rear side surface.

3. The lower receiver of claim 1, wherein the magazine cavity comprises a magazine opening along a bottom side surface of the lower receiver, and wherein the magazine opening is defined by a surface that slopes downward toward a front side surface of the lower receiver.

4. The lower receiver of claim 1, further comprising a plurality of finger recesses located on a front side surface of the lower receiver.

5. The lower receiver of claim 4, wherein the plurality of finger recesses comprises four finger recesses.

6. The lower receiver of claim 1, further comprising a plurality of finger recesses located on a side surface of the first receiver portion.

7. The lower receiver of claim 1, further comprising a plurality of finger recesses located on a side surface of the second receiver portion.

8. The lower receiver of claim 1, further comprising a first opening along a top side surface of the lower receiver and a first hole extending from a left side surface to a right side surface of the lower receiver, wherein the first opening is configured to receive a trigger assembly, and wherein the first hole is configured to receive a trigger pin to secure the trigger assembly within the first opening of the lower receiver.

9. The lower receiver of claim 1, further comprising an integrated trigger guard, wherein the first receiver portion comprises a first portion of the integrated trigger guard, and wherein the second receiver portion comprises a second portion of the integrated trigger guard.

10. A modular firearm comprising:

a lower receiver comprising:

a first receiver portion; and

a second receiver portion configured to mate with the first receiver portion along a mating surface, wherein an inner surface of the first receiver portion and an inner surface of the second receiver portion define a magazine cavity configured to receive a magazine.

11. The modular firearm of claim 10, wherein the mating surface is located along a vertical plane that bisects the lower receiver from a front side surface to a rear side surface.

12. The modular firearm of claim 10, wherein the magazine cavity comprises a magazine opening along a bottom side surface of the lower receiver, and wherein the magazine opening is defined by a surface that slopes downward toward a front side surface of the lower receiver.

13. The modular firearm of claim 10, further comprising a plurality of finger recesses located on a front side surface of the lower receiver.

14. The modular firearm of claim 10, wherein the plurality of finger recesses comprises four finger recesses.

15. The modular firearm of claim 10, further comprising a plurality of finger recesses located on a side surface of the first receiver portion.

16. The modular firearm of claim 10, further comprising a plurality of finger recesses located on a side surface of the second receiver portion.

17. The modular firearm of claim 10, further comprising a first opening along a top side surface of the lower receiver and a first hole extending from a left side surface to a right side surface of the lower receiver, wherein the first opening is configured to receive a trigger assembly, and wherein the first hole is configured to receive a trigger pin to secure the trigger assembly within the first opening of the lower receiver.

18. The modular firearm of claim 10, further comprising an integrated trigger guard, wherein the first receiver portion comprises a first portion of the integrated trigger guard, and wherein the second receiver portion comprises a second portion of the integrated trigger guard.

19. A left side portion of a lower receiver for a modular firearm, wherein the left side portion is configured to mate with a right side portion to form a lower receiver for a modular firearm.

20. (canceled)