Patent Publication Number: US-11035638-B1

Title: Rifle barrel having muzzle device with access ports

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/798,066, filed Jan. 29, 2019. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     The present specification relates to the field of firearms, and more particularly to improvements for a rifle having a muzzle device permanently attached to the barrel. 
     The basic purpose of a rifle is to fire a high-speed projectile, the bullet, towards a target. In a simple form, a rifle&#39;s components may comprise a stock (which may include a buttstock and forestock), a trigger mechanism, a mechanism to load or chamber rounds (for example, a receiver with a bolt action), and a barrel. The rifle fires the bullet from a round or cartridge, which generally includes the bullet (that is, the projectile), a propellant (including for example gun powder) that ignites to produce gases that propel the bullet, a primer to ignite the propellant, and a case that contains the propellant and keeps the other components together. 
     Although the basic purpose is the same, rifles come in a wide variety of designs, including break action rifles, bolt action rifles, lever action rifles, semiautomatic rifles, and fully automatic rifles. Depending on the specific rifle design, the various components may have different characteristics and operation. The barrel is one component that performs a similar function for all conventional rifle designs: it holds and direct the bullet as it is pushed by the expanding gases produced by the propellants. 
     To increase accuracy and performance of the barrel, a variety of devices may be attached to or extend from the front end of the barrel, called the muzzle. These muzzle devices alter the rifle characteristics in some manner, including for example muzzle devices that may diminish the amount of flash, reduce the muzzle rise, lessen the felt recoil, dampen noise levels, or affect a combination of these properties. Typical muzzle devices include shrouds, flash hiders, suppressors, muzzle brakes, and compensators. Muzzle devices maybe removably attached, such as by threading, or permanently attached. 
     Over time and with repeated use, carbon and other deposits can build up on the rifle, including at the tip of the barrel&#39;s muzzle, the crown. These deposits form as a result of propellant burning as well as unburned residue, graphite, and other sources. The deposits can significantly and detrimentally alter barrel accuracy and performance, particularly when the deposits break or become uneven. Rifles with a muzzle device attached to the barrel tend to have a higher rate of carbon deposit buildup at the crown because the muzzle device acts to slow, redirect, or otherwise change the discharge of propellant gases and exhaust from the barrel. 
     These deposits can be removed with commercial solvents or carbon cleaners together with careful, gentle brushing. However, the presence of muzzle devices complicates the cleaning process. If a muzzle device is removably attached, then cleaning may be accomplished by removing the muzzle device first followed by cleaning. For permanently attached muzzle devices, effectively cleaning the crown can be difficult or even impossible, as the barrel crown is deep inside the muzzle device and inaccessible. While a long rod with a brush may be used to reach the crown area, the crown shape and geometry of the barrel and muzzle device often leave areas resistant or insusceptible to cleaning. Moreover, using a brush on a long rod poses an increased risk of damage to the crown, which could ruin the accuracy of the barrel, and crown damage cannot be fixed when the muzzle device is permanently attached. No solution for this problem has been previously identified. 
     The present disclosure describes a novel and effective design that solves the problem of cleaning deposits around the crown of a barrel with a permanently-attached muzzle device, a solution that provides access to the crown when cleaning is required while maintaining normal operation and performance otherwise. 
     SUMMARY 
     Various embodiments of improvements to a rifle barrel with a muzzle device permanently affixed thereto are described herein. In some embodiments, the muzzle device includes one or more lateral ports that allow access to the barrel crown to facilitate cleaning and maintenance of the crown. In some embodiments, the muzzle device includes a sleeve or one or more covers for the ports, which may seal off propellant gases and provide normal functioning of the muzzle device. In some embodiments, the muzzle device includes a detent clip or other means of restraining the sleeve or one or more covers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a barrel with a permanently attached shroud in accordance with one or more embodiments of the present disclosure. 
         FIG. 2  is a side view of a barrel with a permanently attached shroud and sleeve in a closed position in accordance with one or more embodiments of the present disclosure. 
         FIG. 3  is a cross-sectional view of the barrel with a permanently attached shroud of  FIG. 1 . 
         FIG. 4  is an expanded cross-sectional view of the barrel with a permanently attached shroud and sleeve in a closed position of  FIG. 2 . 
         FIG. 5  is a perspective view of a barrel with a permanently attached shroud in accordance with one or more embodiments of the present disclosure. 
         FIG. 6  is a perspective view of a barrel with a permanently attached shroud and sleeve in a closed position in accordance with one or more embodiments of the present disclosure. 
         FIG. 7  is a side view of a barrel with a permanently attached shroud, sleeve in a closed position, and detent clip in accordance with one or more embodiments of the present disclosure. 
         FIG. 8  is a cross-sectional view of the barrel with a permanently attached shroud, sleeve in a closed position, and detent clip of  FIG. 7 . 
         FIG. 9  is a perspective view of a detent clip in accordance with one or more embodiments of the present disclosure. 
         FIG. 10  is a perspective view of a barrel with a permanently attached shroud, sleeve, and detent clip in accordance with one or more embodiments of the present disclosure. 
         FIG. 11  is an expanded perspective view of the barrel with a permanently attached shroud, sleeve, and detent clip of  FIG. 10 . 
         FIG. 12  is a perspective view of a barrel with a permanently attached shroud, sleeve, detent clip, and shims in accordance with one or more embodiments of the present disclosure 
         FIG. 13  is an expanded cross-sectional view of the barrel with a permanently attached shroud, sleeve, detent clip, and shims of  FIG. 12 . 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     The following paragraphs and the attached figures describe in further detail various aspects and embodiments illustrating an improved design for a rifle barrel with a permanently-attached muzzle device, which affords access for cleaning the barrel crown while maintaining normal operation at other times. 
     Rifle barrel  100  comprises an elongated hollow tube used to fire a bullet from a rifle. The hollow interior of the barrel  100  includes a cylindrical-shaped bore  110  defining an axis and having a diameter, caliber  113 , to accommodate bullets of a corresponding size. Common calibers  113  for rifles include 9 mm, .22 Long Rifle (LR), .223 Remington, 5.56×45 mm NATO, .308 Winchester, .40 S&amp;W, and .45 ACP. The barrel  100  has two ends: a muzzle  120 , which is the end of the barrel  100  from which a fired bullet exits, and a rear end  130  that is opposite of muzzle  120  and, in modern rifles, is typically where a round is loaded. Barrel  100  may be formed of various materials capable of withstanding the pressures in firing bullet, including steel, stainless steel, and carbon steel, which are known in the art. 
     The bore  110  of barrel  100  may include rifling, which refers to a pattern of spiral or helical grooves inside bore  110 . The rifling exerts torque on a bullet as it travels the length of bore  110 , thus imparting a spin to the bullet around its longitudinal axis during shooting. This spin serves to stabilize the bullet, improving its aerodynamic characteristics and consequently the firearm&#39;s accuracy over smoothbore designs (i.e., bore designs lacking rifling). 
     The rear end  130  of barrel  100  also typically include a chamber  131 . The chamber  131  is a cavity with larger diameter then caliber  113  so as to accommodate the round&#39;s casing. 
     The muzzle  120  includes a crown  121 , which is located at the tip of muzzle  120 . The crown  121  typically has a concentric, symmetric geometry about the axis of bore  110 . The crown  121  will possess a cross-sectional shape or profile. Common profiles of crown  121  include a perpendicular flat surface, a conical depression (for example, an 11-degree target crown), a recessed or stepped profile (for example, a counterbore), and a smooth, rounded profile. Other geometries may be used for crown  121 , including asymmetric shapes. 
     One purpose of crown  121  is to allow propellant gases to exit the bore  110  of barrel  100  uniformly and with low or minimal resistance. Another purpose of crown  121  may be protecting and shielding the rifling from damage by foreign objects or debris. Depending on the profile, the crown  121  may serve one or both of these purposes, as well as others. 
     Barrel  100  may include a muzzle device to enhance the rifle&#39;s accuracy and performance. A muzzle device is attached to the barrel  100 , including without limitation at the muzzle  120 , and may extend past crown the crown  121 . Although not required, the muzzle device may fully enclose a portion of barrel  100 . To allow the bullet to be fired properly, a muzzle device will include an opening or channel along the same axis defined by bore  110 . The muzzle device&#39;s opening or channel through which the bullet passes is larger in diameter than caliber  113  of bore  110 . Muzzle devices may be formed of steel or lighter metals such as aluminum or carbon fiber. 
     Various muzzle devices known are known in the art, including a shroud, flash hider, suppressor, muzzle brake, or compensator, and these may affect various rifle characteristics, including the amount of flash, reduce the muzzle rise, lessen the felt recoil, dampen noise levels, or a combination of properties. Muzzle devices may be removably mounted to the barrel  100 , including for example by threading on an exterior surface of barrel  100  and corresponding threading on an interior surface of muzzle device. Alternatively, a muzzle device may be permanently mounted to the exterior of barrel  100 . Permanent methods of mounting muzzle device known in the art include full-fusion gas or electric steel-seam welding, high-temperature (1100° F.) silver soldering, and blind pinning with the pin head welded over. 
       FIGS. 1 through 6  illustrate a first embodiment of an improved rifle barrel  100  having a muzzle device, barrel shroud  200 , permanently affixed thereto. 
     As illustrated in  FIGS. 1 through 6 , barrel shroud  200  may comprise an elongated hollow tube attached to the barrel  100  of a firearm or rifle. The interior of shroud  200  includes a bore  210  through which the bullet passes, which is larger in diameter than caliber  113  of bore  110 . The diameter of bore  210  may be larger than a portion of the outer diameter of barrel  100  as well, so as to enclose the barrel  100 . The bore  210  of shroud  200  may have different diameters at different positions along its axis, but in no event less than caliber  113  of bore  110 . 
     Shroud  200  has a rear end  230  that is permanently attached to the barrel  100 , such as by welding or pinning (i.e. pin and weld), and an opposing front end  220  from which the bullet exits. 
     Located between the front end  220  and rear end  230  are one or more lateral openings or ports  240 . The ports  240  may be positioned adjacent to the crown  121  of barrel  100  such that crown  121  is accessible through the ports  240 . As shown in  FIGS. 1 through 6 , the shroud  200  may include two elliptical-shaped ports  240  located on opposite sides of the shroud  200 . However, a different number, shape, and arrangement of ports  240  may be used, including for example a single elliptical-shaped port located above or below crown  121 , multiple narrow ports spaced around shroud  200 , or one or more rectangular ports. The ports  240  may extend equally to the front and rear of crown  121  or, as illustrated in  FIGS. 1 through 6 , they may be positioned closer towards the front end  220  to increase accessibility of the bore  210  immediately in front of crown  121 . 
     As positioned adjacent to crown  121 , the ports  240  allow ready access by a user to clean carbon or other deposits that may have accumulated on crown  121 . 
     To maintain to normal rifle operation and performance when the ports  240  are not being used for cleaning, shroud  200  may further comprise one or more covers for the ports  240 . The first embodiment therefore includes a sleeve  250  adapted to slide along the exterior surface of shroud  200 . In a closed position, shown in  FIGS. 2, 4, and 6 , the sleeve  250  covers the ports  240 . Sleeve  250  may be secured or locked in the closed position on shroud  200  via cooperating components on sleeve  250  and shroud  200 , including for example cooperating threading, tabs and slots, or lugs and grooves. 
     Sleeve  250  may also function to seal off hot, dangerous propellant gases from escaping the ports  240 . For example, sealing is important when the ports  240  are positioned at or near a handguard or another location where a user may grip the firearm. 
     To prevent or minimize propellant gases escaping from ports  240 , shroud  200  and sleeve  250  may include one or more sealing surfaces. The embodiment shown in  FIGS. 1 through 6  includes sealing surfaces to the front and rear of ports  240 . To the front of ports  240 , shroud  200  includes a circumferential external flange  260  that engages and mates with a corresponding interior flange  257  positioned at the front of sleeve  250 . To the rear of ports  240 , the exterior surface of shroud  200  includes threading  265  that engages and mates with corresponding threading  255  on the rear interior of sleeve  250 . When the interior threading  255  of sleeve  250  is tightened onto threading  265 , the respective sealing surfaces mate together and create seals such that propellant gases are substantially trapped inside the shroud  200 . 
     Other sealing means are known in the art and may be applied to seal the ports  240  of shroud  200 . The sleeve  250  or shroud  200  may include one or more gas rings, piston rings, o-rings, or gaskets, including as formed of rubber or metal, to provide a seal. For example, the interior of sleeve  250  may include one or more grooves with one or more rubber o-rings embedded therein that engage the exterior surface of shroud  200  to form a seal. As an alternative to sleeve  250 , shroud  200  may include one or more hinged cover plates, together with one or more latches, allowing the hinged cover plates to be closed and latched to seal ports  240 . 
     By covering and sealing the ports  240  with sleeve  250  or other sealing means, the barrel  100  may functional normally together with shroud  200 . And, when access to the crown  121  is desired for cleaning, the sleeve  250  can be moved from the closed position to an open position to allow a user to clean the crown  121 . 
       FIGS. 7 through 11  illustrate a second embodiment of an improved rifle barrel  100  having a barrel shroud  200  permanently affixed thereto. In the second embodiment, the barrel shroud  200  further comprises a detent clip  280  that engages and applies tension to the sleeve  250  so as to retain it in a closed position on shroud  200 . 
     Referring to  FIG. 9 , the clip  280  may have a semicircular shape, with an elbow  282  at one end and a neck or tab  284  at the other end.  FIG. 8  shows clip  280  engaging both shroud  200  and sleeve  250 , with the elbow  282  located about two-hundred and seventy degrees from the tab  284 . Still referring to  FIG. 8 , the elbow  282  is configured to engage an opening  267  bored into shroud  200  at or near the rearward portion of threading  265 . Referring now to  FIGS. 7 and 8 , tab  284  is configured to engage one of a plurality of slots  252  on the exterior surface of sleeve  250 . The clip  280  may be formed of plastic or steel wire. 
     Various other means for restraining relative movement and providing tension are known in the art and may be applied with respect to sleeve  250  and shroud  200 . For example, springs, including a torsion spring or leaf spring, may be substituted for clip  280 . Similarly, a linear spring bar may be used to engage both the sleeve  250  and shroud  200  and apply tension between them. A set screw or tension screw may be threaded into an opening in either the sleeve  250  or shroud  200  and press against the other to apply tension between the components and restrain movement of sleeve  250  relative to shroud  200 . A ball detent located in either the sleeve  250  or shroud  200 , together with a corresponding indentation in the other to receive the ball, may be used to limit movement of sleeve  250 . A jam nut may be threaded onto sleeve  250  or shroud  200  to apply tension and restrict movement. Finally, a spring latch may be used to engage and apply tension between the sleeve  250  or shroud  200 . The foregoing mechanisms to provide tension and limit movement are well-known in the art. 
       FIGS. 12 through 13  illustrate a third embodiment of an improved rifle barrel  100  with a permanently attached barrel shroud  200 . 
     With heavy use of the rifle, carbon deposits may build up on the interior of sleeve  250  itself, which can make opening the sleeve  250  difficult, particularly when sleeve  250  includes one or more sealing surfaces to limit the escape of propellant gases from ports  240 . Indeed, large carbon deposits may even prevent sleeve  250  from any rotation, essentially locking it into place. 
     As illustrated in  FIGS. 12 and 13 , in the third embodiment the barrel shroud  200  further comprises one or more shims  245  covering the ports  240  under sleeve  250 . The shims  245  may be held in place by the sleeve  250  when in the closed position. Because the one or more shims  245  cover the ports  240  under sleeve  250 , they collect most of the carbon buildup from prolonged use. Consequently, although significant carbon deposits may occur on the underlying shims  245 , the sleeve  250  may still be rotated and removed easily. Because the dirtied shims  245  are simply held in place by sleeve  250 , once the sleeve  250  is removed the shims  245  may be pulled out and cleaned (if reusable) or discarded (if disposable). 
     Shims  245  may be formed as thin plates or sheets, including steel, stainless steel, aluminum, or other metal, and are relatively inexpensive to manufacture. Each shim  245  may be sized to cover a single port  240 . Alternatively, a single shim  245  may substantially wrap around shroud  200  to cover multiple ports  240 . The shims  245  may also comprise an indented tab  247 , or a pin, screw, or other inwardly protruding feature, for positioning the shims  245  relative to the ports  240 . 
     The improvements described in this specification may be applied in a variety of rifles, including pistol caliber carbines. Although the improvements described in this specification are illustrated using shroud embodiments, the improvements may be applied to a variety of muzzle devices. 
     In some circumstances, it may be advantageous for the combined length of the improved rifle barrel and permanently attached muzzle device described herein to equal or exceed a minimum length. For example, in the United States, a rifle with a barrel length (including any permanently attached muzzle device) of less than sixteen inches is subject to the additional requirements of the National Firearms Act, including fees and firearm registration requirements. Similarly, in Europe, a rifle with a barrel length of less than 60 cm may be subject to requirements under the European Firearms Directive. Other countries impose additional requirements for barrel lengths of less than 14.5 inches. As such, the combined length of a rifle barrel and permanently attached muzzle device may exceed a minimum threshold to minimize or avoid registration, fees, and other additional firearm-related requirements. For example, in the United States, a rifle barrel of eight inches would require a permanently attached muzzle device of at least eight inches (for a combined total of sixteen inches) to avoid registration under the National Firearms Act. Similarly, a rifle barrel of five inches would require a permanently attached muzzle device of at least eleven inches to avoid registration in the United States. 
     While the specification describes one or more embodiments, it is not intended to limit the invention or claims to the particular forms set forth. Rather, the specification sets forth the disclosed subject matter by way of example to facilitate discussion. The specification is intended to cover alternatives, modifications, and equivalents as may be included within its spirit and scope. As will be apparent to a person of ordinary skill in the field, the disclosed embodiments are exemplary and not exhaustive of all possible embodiments.