Abstract:
Disclosed herein is a system of components for a compressed-gas-powered gun. The components are made of a transparent polymer, such as polycarbonate. The components are durable, highly attractive, and, because they are clear, permit a user to see through them to determine any gun failure. A method of installing a major component, a breech block, is also disclosed.

Description:
FIELD OF THE INVENTION  
         [0001]    Embodiments of the present invention are directed to clear components for compressed-gas-powered guns, such as paint-ball guns. Guns employing components of the present invention have important aesthetic advantages: they appear far more attractive—or, in the vernacular of the typical user, they look way more cool—than guns made without such components. They have important functional advantages, as well, relating to both their installation and performance (among other things).  
         BACKGROUND OF THE INVENTION  
         [0002]    Compressed-gas-powered guns are used to eject non-lethal projectiles, such as paint balls, plastic pellets, sand bags, and many other projectiles. One of the most popular uses of such guns is to eject paint balls. Paint-ball shooting, at targets and at people (fellow shooters, of course) has become a popular recreational and competitive activity.  
           [0003]    Paint ball players tend to be young males (15-30 years old). Young males, as everyone knows, are attracted to technology, to potentially dangerous things like guns, knives, and skateboards, and especially to things that convey by their appearance that they embody high technology (a high-tech stereo, for example). Technology-advanced dangerous things that look like technologically-advanced dangerous things are therefore the most widely desired things of all.  
           [0004]    Paint-ball gun manufacturers have exploited this concept. Paint-ball guns are designed to look high-tech. Their function often falls short of their appearance, however: components for such guns are typically made of aluminum, which deforms easily, or toy-grade plastic, which breaks easily. And the guns themselves often fail; paint balls frequently rupture inside them, for example. Clear materials, such as glass, for example, permit one to see through them to detect gun failure but they are unable to withstand the extreme pressures and heat the gun generates.  
           [0005]    There is therefore a significant need in the art for paint ball gun components that are durable, that permit one to detect failure in the operation of the gun, and, importantly, that look desirable to prospective purchasers.  
         SUMMARY OF THE INVENTION  
         [0006]    Disclosed herein are components for compressed-gas-powered guns that fill the void in the art for ultra-durable, high-tech—and high-tech looking—components that permit one to discover gun failures. The components are made of a transparent polymer, that is, a polymer with a high luminous transmittance, so that they look clear: imagine a gun-metal black paint-ball gun with a clear plastic barrel, for example, or a deep-blue gun with a clear red plastic breech.  
           [0007]    In a preferred embodiment, the plastic is polycarbonate. To date, no one has successfully used polycarbonate or any other plastic for the major components of compressed-gas-powered gun. This is a source of their aesthetic success: the combination of large areas of clear plastic with metal, a combination that has hitherto been unseen in the art. The components of the invention moreover permit one to discover gun failures. When using a clear breech, for example, one can determine if a paint ball ruptures when the firing bolt strikes it. One could determine if a paint ball becomes lodged in a barrel, obstructing other paint balls and creating a potentially dangerous situation for a user. The components are moreover durable, far more so than aluminum, and are considerably lighter.  
           [0008]    The invention additionally provides for a method of installing a breech according to the invention into a bolt-carrier assembly. Because such assemblies differ widely in their manufacture, it is desirable to make available a breech that will fit within many different such assemblies. It is also desirable to allow the user to install the breech himself, without assistance from a machine shop, and to do so quickly, accurately, and safely. The method of the invention disclosed herein achieves this goal by providing a specially designed rod, also made of a transparent polymer, that both secures the breech to the bolt-carrier assembly and allows a user to easily determine the position of channels to drill into it. Once the user drills holes into the breech he can easily secure it to the assembly with any commonly available fastener.  
       
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0009]    [0009]FIG. 1 is a compressed-gas-powered gun according to the prior art, showing the basic features of such a gun.  
         [0010]    [0010]FIG. 2 is a plan view of a breech block according to one embodiment of the invention.  
         [0011]    [0011]FIG. 3 is a first perspective view of the breech block of FIG. 2.  
         [0012]    [0012]FIG. 4 is a second perspective view of the breech block of FIG. 2, showing a bore through which a projectile is projected and two channels through which the breech block is secured to a bolt-carrier assembly.  
         [0013]    [0013]FIG. 5 is a plan view of a breech block according to another embodiment of the invention.  
         [0014]    [0014]FIG. 6 is a perspective view of a breech block that is similar to the breech block of FIG. 4.  
         [0015]    [0015]FIG. 7 is a perspective view of the breech block of FIG. 4, showing a bore through which a projectile is projected and two channels through which the breech block is secured to a bolt-carrier assembly. FIG. 8 is a view of a bolt according to one embodiment of the invention.  
         [0016]    [0016]FIG. 9 is a bolt-carrier assembly into which the breech block of FIG. 2 has been installed.  
         [0017]    [0017]FIG. 10 is a view of a cylindrical rod used to install the breech block of the invention into a bolt-carrier assembly.  
         [0018]    [0018]FIG. 11 is a side view of the cylindrical rod of FIG. 11 inserted into the bore of a bolt-carrier assembly into which a breech block is installed. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]    Shown in FIG. 1 is a typical prior-art gun powered by compressed gas (various prior-art guns differ as to the details, but most of them have the basic components shown here). The gun  1  comprises a main body  2 , which houses a breech block  3 . A barrel  4  is mounted on the forward end of the main body  2 . The barrel  4  is a hollow cylinder; it thus defines a bore (not shown) through which a projectile emerges from the gun  1  when it is fired. The bore of the gun is usually about 10-15 mm in diameter, corresponding to the diameter of the projectiles which pass through it. The bore extends from the tip  11  of the barrel  4 , through the main body  2  and breech block  3 , where it terminates in a larger chamber (not shown). A firing bolt (not shown), one similar to the bolt shown in FIGS. 8 and 9 but lacking its novel features, is mounted within the bore at the breech block. A hopper  9  holds a plurality, usually 10-100 or more, of projectiles, and communicates with the bore of the main body  2  via a projectile inlet  13 . The projectiles are usually paint balls, but can be other projectiles, such as solid plastic pellets or rubber-coated metal balls. Mounted to the bottom of the main body  2  is a grip frame assembly  6 , comprising a grip  8  and a trigger  7 . The grip is the portion of the gun  1  one grasps to hold it; the trigger, as with any gun, is the portion of gun that fires it. Mounted forward of the grip frame  6 , also on the bottom of the main body  2 , is a gas-inlet regulator body  5 . One or more volumizers  16  (only one is shown; the other is typically positioned above or below the first) are mounted above the gas-inlet regulator body  5  on the front of the main body  2 . At the rear of the main body  2  is a back plate  17 , which extends over most of the surface of the main body  2 , cover any bores or other openings that would otherwise be exposed.  
         [0020]    A container of compressed gas (not shown), typically air compressed to a pressure of around 800-815 psi, delivers gas to the gun via the regulator body  5 . The gas communicates with the main body  2  of the gun  1  via an inlet pipe  10 . The gas-inlet regulator body  5 , and to a lesser extent, the volumizers  16 , regulate the pressure of the compressed gas as it passes from the container through various parts of the gun. A sight  15  is mounted on top of the main body  2  to permit one firing the gun to align it with a target.  
         [0021]    The gun  1  operates typically as follows. Gravity causes a projectile to fall from the hopper  9 , where the projectile is stored, through the inlet  13  into the bore of the main body  2 . The firing bolt is positioned in a retracted position in the breech  3 , immediately behind the projectile. Compressed gas enters an inlet  12 , passes through the gas-inlet regulator  5 , and is expanded somewhat to a pressure of around 400-600 psi. The gas enters, usually through a series of valves, the chamber to the rear of the breech  3 , where the gas builds in pressure. Pulling the trigger  7  causes the gas to vent to the atmosphere through the barrel  4 ; this process causes the firing bolt to move forward rapidly and strike the projectile, thereby launching the projectile through the barrel  4  at high speed.  
         [0022]    Many prior-art guns powered by compressed gas employ the same components of the gun illustrated in FIG. 1—or, at least, employ components that perform a similar function—and operate in the same or similar manner. Examples of such guns include those illustrated in U.S. Pat. No. 6,138,656, U.S. Pat. No. 6,065,460, U.S. Pat. No. 6,035,843, U.S. Pat. No. 6,003,504, U.S. Pat. No. 5,950,611, U.S. Pat. No. 5,896,850, U.S. Pat. No. 5,881,707, U.S. Pat. No. 5,778,868, U.S. Pat. No. 5,771,875, U.S. Pat. No. 5,769,066, U.S. Pat. No. 5,640,945, U.S. Pat. No. 5,613,483, U.S. Pat. No. 5,572,982, U.S. Pat. No. 5,515,838, U.S. Pat. No. 5,505,188, U.S. Pat. No. 5,494,024, U.S. Pat. No. 5,339,791, U.S. Pat. No. 5,161,516, and U.S. Pat. No. 4,936,282, all of the disclosures of which are hereby incorporated by reference. Most of these guns are adapted to fire paint balls.  
         [0023]    The improved compressed-gas-powered gun of the invention comprises a prior art gun, preferably a paint ball gun, in which one or more standard components has been replaced with a component made of the materials disclosed herein. As the term is used herein, “standard components” refers to any of the components illustrated in FIG. 1. It also refers to any component typically found on prior art guns; in particular, it refers to any component illustrated in the foregoing U.S. patents (that is, the patents identified in the preceding paragraph) that has a function that corresponds to the components illustrated in FIG. 1. Preferred such components include the main body  2 , barrel  4 , grip-frame  8 , gas-inlet regulator body  5 , breech block  3 , bolt (not shown), sight  15 , volumizer  16 , and backplate, and also include sub-components of these components. In some prior-art guns, for example, the barrel comprises two parts, a rear barrel and a forward barrel; one could replace the forward barrel (the portion after reference character  18 ) in accordance with the invention and leave the rear portion (usually made of aluminum or other light metal) intact. Components of the invention may be made of any transparent polymer. As used herein, “transparent polymer” refers to any polymer that permits light to pass through it. The desired quality is a substantial degree of luminous transmittance: at least 50% transmittance (in a 50 mm-thick piece) is preferred, and at least 75% is especially preferred. A polymer thus need not have 100% luminous transmittance (it does not, for example, need to be the kind that one can make eye-glass lenses with, though such polymers are suitable) to be considered a transparent polymer for the purposes of this invention. A transparent polymer should also have a reduced haze coefficient, though this quality is far less important than luminous transmittance. Haze is preferably less than about 75%, more preferably less than about 50%, and most preferably less than about 25%.  
         [0024]    Suitable polymers include thermoplastics such as acrylics, polyethylenes, polypropylene, vinyls, nylons, and polycarbonate, and duroplastics such as the aminos (melanine and urea), polyesters, alkyds, and phenolics. Any polymer may be used as long as it has the desired characteristics of luminous transmittance and haze, as previously explained. Thermoplastics are preferred, and polycarbonate is especially preferred. Polycarbonate is available in different colors, such as red, blue, yellow, and clear, and these colors—visible to the user but not compromising the qualities of luminous transmittance and haze—are preferred.  
         [0025]    FIGS.  2 - 7  illustrate two breech blocks according to the invention. In paint ball guns of the prior art, the breech block is a separate component mounted within the main body. In the gun illustrated in FIG. 1, for example, the breech block is pivotally mounted on the main body. In preferred embodiments of the present invention, the breech block is a removable component, as is illustrated in FIG. 1; in especially preferred embodiments, the breech block is pivotally mounted on the main body, in a manner to be described later. It will be apparent to one skilled in the art of compressed-gas-powered weapons, however, that the breech blocks of the invention need not be removable or pivotally mounted. Instead, they may be a permanent fixture of the main body, integrated so as preclude its removal from the main body.  
         [0026]    [0026]FIG. 2 is a plan view of a breech block according to one embodiment of the invention. The breech comprises a solid block of transparent polymer having dimensions that are typical of a breech for a prior art gun. The main body of the breech is a cylinder, defined (in cross-section) by arcs  51  and  52 . Its diameter  50  is preferably from about 1 inch to 2 inches, which is typical of most prior art guns, although the diameter may be as large or small as the gun requires. In an especially preferred embodiment, diameter  50  is approximately 1.25 inches.  
         [0027]    The top of the breech  55  is flat and is usually 40-80% of the length of the diameter  50  of the cylindrical main body. In the embodiment shown in FIG. 2, the top  55  has a length of 60% that of diameter  50 , and this ratio of diameter to top length is preferred. The bottom  60  of the breech is also flat, and is also usually 40-80% of the length of the diameter  50 , though the bottom need not be of the same length as the top  55 . In the embodiment shown in FIG. 2, for example, the bottom  60  is 75% of the length of the top  55 , and this ratio of diameter to bottom length is preferred.  
         [0028]    Two lugs  70  project from the bottom  60  of the breech. The lugs are defined by a cylinder having a diameter  75  that is from about 5 to 30% of the diameter  50  of the main body. In the embodiment illustrated in FIG. 2, the diameter  75  of the lugs  70  is about 10% of the diameter  50  of the main body, and this ratio of main-body diameter to lug diameter is preferred. The lugs connect smoothly to the main body of the breech via a straight line  80  that deviates at angle θ from a line  85  that is perpendicular to the bottom  60 . Angle θ can be any angle required to accommodate the diameter  75  of the lug, but is generally from 20° to 30°. A preferred angle θ is 24° to 26°.  
         [0029]    [0029]FIG. 3 is a perspective view of the breech block of FIG. 2 showing grooves  90  and other variations that may be added to its surface. The top  55 , bottom  60 , and lugs  70  of the breech are visible, and one can now appreciate that features illustrated in the plan view of FIG. 2 (such as the lugs  70 ) extend throughout the length of the breech. The length of the breech is anywhere from about ½ inch to 6 inches or more, but in preferred embodiments ranges from about 2 to 3 inches.  
         [0030]    [0030]FIG. 4 is a second perspective view of the breech block of FIG. 2. Shown is a bore  100  in which a firing bolt (not shown) is placed and through which a paint ball or other projectile is ejected. The bore  100  has a diameter that is dictated by the projectile the gun is designed to fire. In a preferred embodiment, the breech is design to accommodate a paint ball having a diameter of approximately 17.5 mm; so the diameter of the bore  100  is only very slightly larger than that. The bore of the breech must be aligned with the bore of the bolt-carrier assembly into which the breech is inserted, such that a smooth continuous bore is created along the entire path of the projectile. The position of the bore is usually very closely near or at the center of the breech, although it may vary from this position as required by the bolt-carrier assembly with which it is designed to be used.  
         [0031]    Smaller channels  110  in the breech correspond to similar channels in the bolt carrier assembly (not shown) in which the breech is placed. By inserting a pin, rod, or -other fastener into the channels  110 , one can secure the breech to the bolt-carrier assembly in a manner that allows the breech to pivot with respect to the bolt-carrier assembly when the fasteners on one side of the breech are released. The channels may be either pre-drilled, or, as will be described later, may be drilled by a user prior to installing the breech in the bolt-carrier assembly. Most bolt-carrier assemblies have channels of a pre-determined diameter already drilled to receive a fastener from a breech. The diameter of the channels  110  in the breech, therefore, should be the same as the diameter of the channels in the bolt carrier assembly. The length of the channels, if pre-drilled, may be anywhere from ⅛ of an inch to the entire length of 85 of the breech.  
         [0032]    [0032]FIG. 5 illustrates a breech block according to another embodiment of the invention. Like the breech block of FIG. 2, the breech block is a polyhedron, but it has a polygon for a base instead of a circle (or a semi-circle). The width of the base at its midpoint, indicated by the line at  150 , is the same as the diameter  50  of the breech illustrated in FIG. 2, that is, 1 inch to 2 inches, although it may be as large or small as the gun requires. In an especially preferred embodiment, width  150  is approximately 1.25 inches. The top of the breech  155  is flat and is usually 40-80% of the width  150  of the breech at its midpoint. In the embodiment illustrated in FIG. 5, for example, the width of the top  155  is approximately 65% of the width of the breech at its midpoint, and this width is preferred. The bottom  160  of the breech is also flat, and is usually about 60-95% of the width  150  of the breech at its midpoint. The bottom need not be the same width as the top. In a preferred embodiment, the bottom is 95% of the width of the breech at its midpoint, as shown in FIG. 5.  
         [0033]    As with the breech of FIG. 2, two lugs  170  project from the bottom  160  of the breech. The lugs  170  are substantially similar to the lugs  70  shown in FIG. 2: they are defined by a cylinder having a diameter  175  that is from about 5 to 30% of the width  150  of the breech at its midpoint, and connect smoothly to the main body via a straight line  180  that deviates at by 20° to 30° (θ) from a line  185  that is perpendicular to the bottom  160 . The diameter  175  of the cylinder is preferably 10% of the width  150  of the breech at its midpoint; and angle θ is preferably 24° to 26°.  
         [0034]    The top  155  of the breech is formed by a straight line that connects via an arch  190  to the sides  195  of the breech. The angle φ between the sides  195  of the breech and its top  155  can vary anywhere from about 95 to 135°, depending, of course, on the ratio of the width of the breech  150  at its midpoint to its width  155  at the top. In a preferred embodiment, this angle is about 98.5°.  
         [0035]    [0035]FIG. 6 is a perspective view of a breech block that is substantially similar to the breech block shown in FIG. 5. It differs in that the arch  190  which connects the side of the breech  195  to the top  155  is almost imperceptibly small; and in that the angle φ 2  formed by the side  195  and the top  155  is smaller than the angle φ 1  of the sides  195  and top  155  of the breech shown in FIG. 5. The top  55 , bottom  60 , and lugs  70  of the breech are visible, as are text and other indicia  199 . The length of the breech  198  is from about ½ inch to 6 inches or more; a length of 2 to 3 inches is preferred.  
         [0036]    In the embodiment shown in FIG. 6, the length of the breech  196  is defined by an arch along its top. The curvature of this arch is not important, as long as it does not descend, of course, to a point below the bore (which has yet to be drilled in the breech shown in FIG. 6). The curvature may therefore vary, even considerably, and still achieve the objects of the invention.  
         [0037]    [0037]FIG. 7 is a perspective view of the breech block of FIG. 4. Shown is a bore  100 , having a position and size as previously described. Small channels  210  correspond to similar channels in the bolt carrier, but in this embodiment, the channels run the entire length of the breech. As with the embodiment illustrated in FIG. 4, the channels accommodate fasteners which secure the breech to the bolt-carrier assembly.  
         [0038]    [0038]FIG. 8 illustrates a bolt according to the invention. In its resting state—that is, the state just prior to the expulsion of gas into the firing chamber—the bolt sits within the breech, with a projectile placed just after the forward end  310  of the bolt. The bolt comprises a cylinder divided into four sections. The bolt can be anywhere from about ½ to 4 inches in length, but is preferably between 2 and 3 inches, and is most preferably 2.5 inches. The first section, designated section 1, is approximately 25%-45% of the length of the bolt, and is preferably 35%. It comprises a cylinder that is of uniform diameter for a length equivalent to 1%-10%, and preferably 5%, of the length of the bolt, and begins to taper thereafter until the forward end  310 . The uniform portion has a diameter equivalent to the diameter of the bolt  315  at its widest portion; this diameter is approximately equivalent to the diameter of the projectile the gun fires, and is only very slightly less than the diameter of the bore. The taper can be uniform, or it can vary, but in all cases results in a diameter  320  at the forward end  310  of the bolt that is between 55% and 80% of diameter  315 .  
         [0039]    The second section  11  has a length of about 2% to 10% of the bolt, and is preferably 5% of the bolt. It comprises a disk that tapers to a thickness of about {fraction (1/32)} to {fraction ( 1 / 16 )} inch. The rate of taper is uniform with respect to each side, but need not be the same between sides (one side may taper gradually and uniformly, for example, while the other may taper suddenly and uniformly). The diameter of the disk at its rim is equivalent to the diameter  315  at the widest part of the bolt. The third section III has a length of about 5-15% of the bolt, and is preferably 10% of the bolt. The diameter of this portion is uniform, and is about 25%-75% of the diameter  315  at the widest part of the bolt; preferably this diameter is 50% of diameter  315 .  
         [0040]    The fourth section IV has a length of about 10-30% of the bolt, and is preferably 20% of the bolt. It comprises three disks that taper in the same manner and have the same dimensions as the disk of section  11 . The fifth section has a length of about 20 to 40% of the bolt, preferably 35%, and a uniform diameter equivalent to the diameter 315 of the widest part of the bolt.  
         [0041]    [0041]FIG. 9 shows a bolt-carrier assembly  420  of the prior art into which a breech  450  of the invention has been inserted. The breech  450  comprises a transparent plastic that defines a bore and smaller channels  410  (similar to the channels designated  110  in FIG. 4) for fastening the breech  450  to the assembly  420 . The fasteners may be any fastener known in the art suitable for such an arrangement; that is, any fastener that can join two pieces by securing one channel to another. Any nail-shaped or rod-shaped piece will do, such as screws, nails, and the like. In a preferred embodiment, the fastener is a spring-loaded metal rod.  
         [0042]    A breech according to the invention may be supplied with channels  410  already pre-drilled, but it is preferably supplied without such channels. This is because the bolt-carrier assembly  420  into which the breech  450  is inserted varies considerably by manufacturer and model. The position of the channels in the bolt-carrier assembly differ, as do their size and length. For this reason, supplying the breech without any channels drilled (such as that illustrated in FIGS. 3 and 6) is preferred. This allows a user to drill channels in the breech that precisely match channels in the bolt-carrier assembly.  
         [0043]    To drill channels in the breech  450 , one first inserts the breech  450  into the bolt-carrier assembly  420 . One then selects the appropriate size drill bit, which should correspond to the size of the channel formed in the bolt-carrier assembly. To proceed, it is necessary to stabilize the breech; failing to do so compromises accuracy (the breech may move and one may drill in the wrong place) and safety (the drill bit may move and injure the user).  
         [0044]    A rod, illustrated in FIG. 10, is used to stabilize the breech within the bolt carrier assembly. One inserts the rod into the bore through the front end  430  of the bolt-carrier assembly and pushes it into the breech  450 . Because portions of the rod have a diameter greater than the diameter of the bore, pushing the rod into the bore with a small amount of force will firmly secure the breech and bolt-carrier along the axis of the bore.  
         [0045]    The rod is typically 1.5 to 5 times the length of the breech, but may be longer or shorter, as required. In a preferred embodiment, the rod is 2.5 times longer than the breech, or approximately 6 inches. What is important is that the rod be at least longer than the distance between the front end  430  of the bolt-carrier assembly and the front end  440  of the breech; if the rod is shorter, it will not project into the breech and will fail to secure it to the bolt-carrier assembly.  
         [0046]    The rod is of uniform diameter along most of its length. The diameter  465 ,  485  at the front end  460  and the back end  485  are therefore approximately equal, although they need not be. Between a first point  470  along the rod and a second point  475 , the diameter increases and is greater than the diameter of the rod  485  at the back end  480 .  
         [0047]    The diameter  485  of the rod at the back end is slightly less than the bore of the breech and the bolt-carrier assembly, and is uniform until second point  475 ; the diameter after the second point  475  increases gradually until the first point  470 , at which it becomes slightly greater than the diameter of the bore. In a first embodiment, the diameter of the rod decreases again after the first point  470  until it is equal again to the diameter  485  at the back end  480 . In a second, and preferred embodiment, the diameter is uniform between the first point and the back end  480 ; that is, it remains slightly greater than the bore.  
         [0048]    The second point  470  is preferably closer to the front end  460  than the back end  480 , although it need not be. Points  475  and  470  are positioned from ⅛ inch to 2 inches apart, and are preferably positioned ½ inch apart.  
         [0049]    After one inserts the breech  450  into the bolt-carrier assembly  420 , one inserts the rod of FIG. 10 into the bore. One inserts the end (in this case, the back end) with the diameter less than the bore first; upon pushing the rod in from the opposite end  460 , the rod will travel until the second point  470  reaches the bore. Because the rod increases in diameter gradually between points  475  and  470 , one can achieve a very snug fit, thereby securing the breech  450  within bolt-carrier assembly tightly enough to prevent a drill bit from moving it.  
         [0050]    The first and second points  475  and  470  are preferably positioned such that the rod travels through the bore and stops at a point  495  (or, alternatively, at point  490 ) that demarcates the length of the channel to drill into the breech  450 . The length, as illustrated in FIG. 11, is that defined between points  495  (the point to which the proximal end  480  of the rod extends) and the back end  496  of the breech. A cut along the circumference of the rod  490  demarcates a second length: the length of the channels is thus defined between the cut  490 , which is visible through the transparent breech, and the front end  491  of the breech. By positioning the rod fully in the bore, therefore, one can at once secure the breech to the bolt-carrier assembly, and can determine the length of channels to cut it. The last step in the process comprises inserting a drill bit through the bolt-carrier assembly and into the breech to make these channels.