Patent Publication Number: US-2022221238-A1

Title: Timing, fastening, and sealing features for firearm gas blocks

Description:
PRIORITY 
     This application is a continuation-in-part of U.S. patent application Ser. No. 17/142,736, filed on Jan. 6, 2021, entitled ADJUSTABLE FIREARM GAS BLOCK, which claims priority to U.S. Provisional Application No. 62/957,731 filed on Jan. 6, 2020, entitled ADJUSTABLE FIREARM GAS BLOCK, each of which is incorporated by reference herein. 
    
    
     BACKGROUND 
     Typical firearms propel a bullet or other type of projectile through the expansion of gas within a firearm barrel. The majority of the gas may be expelled out of the front of the firearm barrel together with the bullet. However, some firearms may exploit a portion of the gas to automatically cycle the action of the firearm (e.g., “charge” the firearm), which may include ejecting the used casing and reloading another round of ammunition into the firing chamber. This portion of the gas may be expelled from a gas port located on the barrel. The expelled gas may be channeled by a gas tube back to the upper receiver so that it may be used to “charge” the firearm. 
     Some firearms may have a gas block located on the barrel to connect the gas port located on the barrel to the gas tube. This gas block, if positioned in a correct location on the length of the barrel during firearm assembly, and in a correct angular orientation, may prevent gas leaks and ensure that a sufficient amount of gas enters the tube to drive the action of the firearm. If the gas block is not positioned on the correct location or in a correct angular orientation during firearm assembly, an ingress port on an interior of the gas block may be partially misaligned with the gas port located on the barrel. This partial misalignment may reduce the amount of gas entering the gas tube, which could cause other firearm components to regularly or intermittently cycle incorrectly when fired (leading to regular or intermittent jams during firing). Since the gas block covers the gas port located on the barrel, both the gas port and the ingress port on the interior of the gas block are hidden from view once the gas block is slipped over the barrel, which makes positioning the gas block in the correct angular orientation difficult. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a timing system for a firearm gas block, according to various embodiments. 
         FIG. 2  illustrates a view of the timing system of  FIG. 1  in which the gas block has been pulled away from the shoulder, according to various embodiments. 
         FIG. 3  illustrates a top view of the timing system of  FIG. 1 , according to various embodiments. 
         FIGS. 4A and 4B  illustrate sectional top views of one embodiment of an adjustable firearm gas block in which the adjustable firearm gas block is arranged for use with the firearm barrel assembly described with respect to  FIGS. 1-3 . 
         FIG. 5  illustrates a front view of the adjustable firearm gas block of  FIGS. 4A and 4B . 
         FIG. 6A  illustrates a front end view of the adjustable firearm gas block of  FIGS. 1-4B , and  FIG. 6B  illustrates a cross-sectional view taken along section line F of  FIG. 6A . 
         FIG. 7A  is a front view of another embodiment of an adjustable firearm gas block. 
         FIG. 7B  is a isometric view showing visual indicators on a sidewall of a head of the gas block screw of the adjustable firearm gas block shown in  FIG. 6B . 
         FIG. 8  illustrates an isometric view of another adjustable firearm gas block, according to various embodiments. 
         FIG. 9A  illustrates a cross-sectional view of the adjustable firearm gas block of  FIG. 8 , according to various embodiments. 
         FIG. 9B  illustrates a partial cross-sectional view taken along section line E of  FIG. 9A . 
         FIG. 9C  illustrates a cross-section view of the barrel illustrated in  FIG. 9A  at a taper interface. 
         FIG. 9D  illustrates the tapered fastener of the adjustable firearm gas block of  FIG. 8 . 
         FIG. 10  illustrates another cross-sectional view of the adjustable firearm gas block of  FIG. 8  in the fully open state. 
     
    
    
     DETAILED DESCRIPTION 
     Timing System for Firearm Gas Block 
     A shoulder may be formed behind a location for a gas block by selectively removing material when the barrel is machined, and this shoulder fixes the position of the gas block in the lengthwise position. However, known shoulders do not prevent mis-timing the gas block (say, a wrong angular orientation in which gas flow is significantly impeded). As a result, firearm manufacturers may use a tool called a jig to time the gas block (to achieve the required orientation). When using the jig, the barrel is installed in the upper receiver, and then the jig is used to position the gas block relative to the upper receiver (the jig is used to time the gas block). With the gas block timed, pinning holes can then be drilled through the gas block and partially into the barrel, pins can be inserted into the pinning holes, so that the position of the gas block is fixed before removing the jig. 
     The use of the jig to time the gas block requires significant additional labor to assemble the firearm, raising manufacturing costs. One jig-less manufacturing method uses screws in place of pins. An attempt is made to predrill shallow template “dimple” in the barrel (on the gas block journal on which the gas block is to be slide over) before sliding on the gas block. The challenge comes from trying to align screw tips of screws used to fasten the gas block to the barrel into the predrilled shallow holes in barrel without the benefit of sight. Without experience on the part of the installer, due to the lack of visibility in attempting to find a template obscured by the gas block, a person could mistake the screw tip biting into the surface of the barrel for finding the template, and thus secure the gas block in a misoriented position. 
       FIG. 1  illustrates a timing system for a firearm gas block, according to various embodiments.  FIG. 2  illustrates of view of the timing system of  FIG. 1  in which the gas block has been pulled away from the shoulder. Although this particular example is for an AR15, it should be appreciated that any of the features illustrated or described herein may be used in any firearms having gas-operation systems (including direct impingement systems, piston-driven systems, and any other gas operation system now known or later developed).  FIG. 3  illustrates a top view of the timing system of  FIG. 1 . 
     Referring now to  FIG. 2 , the timing system includes the timing notch  11  located on the shoulder and the timing boss  21  located on the end of the gas block  20 . The timing notch  11  may be formed by selectively machining the barrel or the shoulder, for example, by recessing the planar surface of the shoulder using a milling cutter. In the illustrated example, the timing notch  11  may be formed by recessing the shoulder. The timing boss  21  may be formed by selectively machining the gas block  20 . 
     The timing system including the timing notch  11  and the timing boss  21  is for timing the gas block  20 , and may be independent from fasteners used to secure the gas block  20  once timed. Any known fasteners (not shown) may be used in combination with any gas block using the timing system (such as set screws located at the bottom of the gas block  20  (not shown) to pull the bore of the gas block against the barrel). The timing system may also be independent from the illustrated hole  1  on the side of the gas block (this hole  1  is for pinning the end of a gas tube (not shown) into the gas block at the large hole  2  shown in the illustration). 
     Referring now to  FIGS. 1 and 3 , when the timing boss  21  is located in the timing notch  11  as shown, the gas block  20  is in the correct rotational orientation to position an ingress port on the interior of the gas block  20  over the gas port  12  ( FIG. 2 , the gas port  12  located on the barrel) with no misalignment. 
     Unlike the use of a template and screws, the timing system is independent of the fasteners used (so an operator need not have the expertise to feel the difference between a template and a screw biting into a barrel). The timing notch  11  and the timing boss  21  may be integrally formed as part of the shoulder and the gas block, respectively, hence fastener parts like pins required to time the gas block in some other systems may not be required. 
     In the illustrated embodiment, the timing boss  21  may be dimensioned so that the tip of the timing boss  21  does not contact the closed end of the timing notch  11  (a small gap  15  is shown between the tip of the timing boss  21  and the closed end of the timing notch  11 ). In this example only the sides of the timing boss  21  may make contact, as shown in more detail in  FIG. 3  (the timing boss  21  may have a width arranged to fit into the timing notch  11  and a height selected to form the gap  15  when the timing boss  21  is in the timing notch  11 ). The gap  15  may be provided to ensure that the gas block  20  contacts the shoulder (such contact provides alignment in the lengthwise direction). However, in other embodiments, the sides and tip of the timing boss  21  may contact the timing notch  11 . For instance, in one embodiment, the shoulder may be cut with long shallow notches to form a wavy surface defining timing indentations around the shoulder. In such an embodiment, the end of the gas block may be cut similarly to form wide timing protrusions to fit in the timing indentations. 
     In other embodiments, the barrel may not include a shoulder. The barrel can be selectively machined to leave an integrated projection (such as a column, post, or the like) that fixes a position of a gas block in the linear direction and is wide enough to cut a timing notch. In this embodiment, the sides and tip of the timing boss may make contact with the timing notch (that is cut into the projection) to fix the position of the gas block in the linear direction and angular orientation. 
     In yet further examples, the integrated projection of the barrel may form a timing protrusion (such as a timing boss) and a timing indentation may be cut into the end of the gas block. 
     The gas block shown in the figures does not include a slit. Some gas blocks may include a slit (say at the bottom of the gas block) to allow the gas block to expand to slide onto the journal. Fasteners may close the slit to clamp the gas block onto a journal of the barrel. Any timing system described herein may be used with this type of gas block, or any other type of gas block available today, or later developed. Any timing system described herein may be used in combination with any adjustable firearm gas block described herein or designed in U.S. Provisional Patent Application 62/861,827 (filed Jun. 14, 2019) and U.S. patent application Ser. No. 16/900,161 (filed Jun. 12, 2020), each of which is incorporated by reference herein. 
     In one example, a barrel assembly for a firearm is provided. The barrel assembly may include a barrel having a gas port and a shoulder or other projection; a gas block around the barrel and covering the gas port, wherein an end of the gas block faces the shoulder of the barrel or the other projection of the barrel; and a timing system including a timing protrusion and a timing indentation, the timing system to rotationally orient the gas block to position an ingress port of the gas block over the gas port (located on the barrel) when the timing protrusion is positioned in the timing indentation, wherein one of the timing protrusion and the timing indentation is formed at the end of the gas block and the other one of the timing protrusion and the timing indentation is formed at the shoulder of the barrel or the other projection of the barrel. 
     In one example of this barrel assembly, the timing indentation comprises a single timing notch and the timing protrusion comprises a single timing boss. 
     In one example of this barrel assembly, the timing protrusion is integrally formed on the end of the gas block. 
     In one example of this barrel assembly, the timing indentation comprises a cut into a side of the shoulder of the barrel or the other projection of the barrel. 
     In one example of this barrel assembly, the barrel assembly may further include one or more fasteners to pull the bore of the gas block against a journal of the barrel, wherein the timing system is separate from the fasteners. In one example, the one or more fasteners are installed on a first side of the barrel, and wherein the timing system is located on a second opposite side of the barrel. 
     In one example of this barrel assembly, the gas block defines a slit, and wherein the one or more fasteners close the slit to clamp the gas block onto a journal of the barrel. 
     In one example of this barrel assembly, the shoulder of the barrel or the other projection of the barrel includes a surface that makes contact with a surface of the end of the gas block when the timing protrusion is positioned in the timing indentation, wherein the timing indentation comprises a hole formed in one of the surfaces. 
     In one example of this barrel assembly, the barrel assembly includes a gap located between a tip of the timing protrusion and an end of the timing indentation when the surfaces are in contact. 
     In one example, a firearm is provided. The firearm may include a barrel having a gas port and a shoulder or other projection; a gas block around the barrel and covering the gas port, wherein an end of the gas block faces the shoulder of the barrel or the other projection of the barrel; and a timing system including a timing protrusion and a timing indentation, the timing system to rotationally orient the gas block to position an ingress port of the gas block over the gas port (located on the gas barrel) when the timing protrusion is positioned in the timing indentation, wherein one of the timing protrusion and the timing indentation is formed at the end of the gas block and the other one of the timing protrusion and the timing indentation is formed at the shoulder of the barrel or the other projection of the barrel. In one example, the firearm comprises an AR-15. 
     In one example of this firearm, the timing indentation comprises a single timing notch and the timing protrusion comprises a single timing boss. 
     In one example of this firearm, the timing protrusion is integrally formed on the end of the gas block. 
     In one example of this firearm, the timing indentation comprises a cut into a side of the shoulder of the barrel or the other projection of the barrel. 
     In one example of this firearm, the firearm may further include one or more fasteners to pull an underside of the gas block against a journal of the barrel, wherein the timing system is separate from the fasteners. In one example, the one or more fasteners are installed on a first side of the barrel, and wherein the timing system is located on a second opposite side of the barrel. 
     In one example of this firearm, the gas block defines a slit, and wherein the one or more fasteners close the slit to clamp the gas block onto a journal of the barrel. 
     In one example of this firearm, the shoulder of the barrel or the other projection of the barrel includes a surface that makes contact with a surface of the end of the gas block when the timing protrusion is positioned in the timing indentation, wherein the timing indentation comprises a hole formed in one of the surfaces. In one example, the firearm further includes a gap located between a tip of the timing protrusion and an end of the timing indentation when the surfaces are in contact. In one example, the surfaces comprise planar surfaces. 
     Adjustable Firearm Gas Block 
     A user may desire to restrict the flow of gas from a gas port  12  ( FIG. 2 ) into the gas tube, e.g., a gas tube installed into the opening  2  ( FIG. 2 ) at the end of the gas block  20  ( FIG. 2 ). The performance advantages of restricting this gas flow are known, such as to compensate for the user of a suppressor and/or to modify the performance of the firearm. As is known, this gas flow can be reduced down to the minimal level needed to automatically cycle the firearm or reduced down even further in which case the user will manually cycle the firearm. 
     A known adjustable firearm gas block is described in U.S. Pat. No. 9,410,756. In the known adjustable firearm gas block, an adjustment screw is tightened down a user-selectable amount to reduce the gas flow as desired. To keep the adjustment screw from unintentionally rotating again after selecting a position, an axial groove is provided in the threaded section of the adjustment screw. A detent plunger may engage this axial groove in various rotational positions of the axial screw. This arrangement requires a number of individual components—a detent slot for the leaf spring, a fastener to hold down one end of the leaf spring, a detent bore for holding the detect plunger between the adjustment screw and the other end of the leaf spring. 
     Various known adjustable firearm gas blocks are cost prohibitive to manufacture and/or suffer other drawbacks. An improved gas block may reduce manufacturing costs and/or provide other benefits compared to known adjustable firearm gas blocks. 
       FIG. 4A  illustrates a sectional top view of one embodiment of an adjustable firearm gas block  300  in which a section of the gas block above a centerline of a gas metering screw  31  has been removed.  FIG. 4B  illustrates another sectional top view in which a head  41  of the gas metering screw  31  and a head  42  of a spring pin  32  above a centerline of the heads  41  and  42  are also similarly sectioned. Since this embodiment of an adjustable firearm gas block is arranged for use with the barrel assembly described with respect to  FIGS. 1-3 , the timing boss  21  ( FIG. 2 ) is present in this embodiment. It should be appreciated that any adjustable firearm gas block features described herein can be used in any known barrel assembly whether or not that barrel assembly includes any of timing system features described with respect to  FIGS. 1-3 . 
     The adjustable firearm gas block  300  includes a gas metering screw  31  having a head  41  drivable to position an end  45  of the gas metering screw  31  into a channel over the ingress port  35 , which impedes the flow of gas from the gas port  12  ( FIG. 2 ) to a gas tube inserted in the opening  2  ( FIG. 2 ). A spring pin  32  has a head  42  that makes contact with the head  41  of the gas metering screw  31 . 
     The head  41  has a plurality of indentations  43  and areas between the indentations  43 . When the head  42  makes contact with the area between the indentations  43 , the spring pin  32  is not relaxed. When the head  42  is aligned with one of the indentations  43 , the spring pin  32  may relax (e.g., completely relax in some embodiments).  FIG. 5  illustrates a front view in which a pointed tip  51  of the spring pin  32  is shown in one of the indentations  43 . 
     In this example, the plurality of indentations  43  are formed by removing material from a cylindrical sidewall of the head  41 . In other examples, a sidewall of a head of a gas metering screw may have bumps formed therein. In such an example, a sidewall of the head of a spring pin may have a gap to mate with the bumps. No force (or a small force) may be applied to the head of the gas metering screw (by the head of the spring pin) when an individual one of the bumps is positioned in the gap. A larger force may be applied to the head of the gas metering screw (by the head of the spring pin) when there is no alignment of any of the bumps with the gap. Although the sidewall of the head  41  is cylindrical in this embodiment, in other embodiments the sidewall may have any number of flats (such as hexagonal column shape in one example). In examples in which the sidewall has flats, the vertex (where the flats meet) may be the “bumps” that interface with an indentation on the spring head. 
     In one example in which the spring pin  32  ( FIGS. 4A and 4B ) may be completely relaxed when the pointed tip  51  of the head  42  is aligned with the one of the indentations  43 , the indentations  43  may be deeper than a height of the pointed tip  51 . This may allow the pointed tip  51  to be located in a void of one of the indentations  43  without any contact of the top of the pointed tip  51  and the bottom of the void. This may allow the spring pin  32  to completely relax, which may increase longevity. This feature may allow a very slight rotational movement of the gas metering screw  31  when aligned, which gives a user feedback that alignment has been achieved (and in the middle of this slight rotational range there may be zero contact between the heads  41  and  42 ). In such an example, the slope of the pointed tip  51  may be linear and the slope of the indentations  43  may be non-linear (e.g., curved), although such a feature may not be required to provide the user feedback (the slopes can be the same if the void is larger than the pointed tip  51 ). 
     Referring again to  FIGS. 4A and 4B , the system  300  may be arranged to fully obstruct the channel over the ingress port  35  with the end  45  of the gas metering screw  31 . In this state, an end  91  of the head  41  may align with an alignment feature (such as an end  92  of the head  42  of the spring pin  32 ) to indicate to the user that the channel over the ingress port  35  is fully obstructed. Also, in various embodiments, the head  41  may have circumferential markings  49  (e.g., indentations or bumps in other examples). In the case of more than one indentation, an innermost one of the circumferential markings  49  (e.g., indentations or bumps in other examples) may align with the alignment feature (e.g., the end  92  of the head  42 ) in the fully open position (as illustrated). Another one of the circumferential markings  49  (e.g., the indentations or bumps in other examples) may align with the alignment feature (e.g., the end  92  of the head  42 ) in a state between fully open and fully closed, e.g., half open in the present example. In this example, the end  92  of the head  42  of the spring pin  32  is a planar face and the end  91  of the head  41  of the gas metering screw  31  is a planar face, however, this is not required (in other examples, an end of the spring pin  32  may be a curved face or some other end and/or the end of the gas metering screw  31  may be a curved face or some other end). 
     Also, in this example, the adjustable firearm gas block includes the spring pin  32 . In other examples, an adjustable firearm gas block may include the gas metering screw  31  and some other mechanism (e.g., now known of later developed) to preserve the rotational position of the gas metering screw  31 . This mechanism may include a columnar projection extending from a front face of the adjustable firearm gas block  300  (similar to how spring pin  32  extends from the front face), or may be any other mechanism behind the front face of the adjustable firearm gas block  300  (e.g., at least partially inside the adjustable firearm gas block  300 ). In various embodiments, the alignment feature may be an end of the columnar projection or the front face of the adjustable firearm gas block. 
     Referring again to  FIG. 5 , the end  91  of the head  41  may include a reference marking  59  such as an indentation (or bump in some other example) alignable with a predefined reference to aid a user in tracking the position of the gas metering screw  31 . In this example, the predefined reference is the pointed tip  51 . However, in other examples, the predefined reference can be some other projection, indentation, or marking on a side or end of the head  42  of the spring pin  32 . A user may count “clicks” from alignment of this reference marking  59  with the predefined reference for fine adjustment tracking (together with the course adjustment tracking described with reference to  FIGS. 4A and 4B ) as the user tries different gas restriction settings. 
     In some examples, optionally, a position of the gas metering screw  31  may be timed in the threaded hole so that alignment of the reference marking  59  with the predefined reference coincides with optimal alignment of the circumferential marking  49  with the alignment feature. In this way, a user can judge whether one of the circumferential markings  49  is exactly aligned with the alignment feature (e.g., in the illustrated example the end  92  of the head  42  of the spring pin  32 ). However, timing the position of the gas metering screw  31  is not required in various embodiments. 
     According to variously described examples above, the predefined reference is part of the head  42  of the spring pin  32  (e.g., part of the sidewall of the spring pin  32 ). In other examples, the predefined reference may be a mark on the end  92  of the head  42  of the spring pin  32 , or a mark on the face of the front end of the adjustable firearm gas block  300  in embodiments without a columnar projection such as the spring pin  32 . 
     Referring to  FIGS. 4A and 4B and 5  in combination, it may be possible in some examples for a user to grip the head  41  (aided by the indentations  43  the indentations of the circumferential markings  49  in some examples) for tool-less adjustment of the gas metering screw  31 . In any event, in the illustrated embodiment a user may use a hex wrench in the hex socket illustrated on the end  91  of the head  41  in  FIG. 5 . In other examples, any other type of drive mechanism can be used (e.g., some other type of socket and or wrench). In example in which the head  41  has any number of flats (such as a hexagon columnar shape as one example), the head  41  may be sized to mate with a wrench to drive the head  41  (the wrench may receive the hexagonal columnar shaped head  41 ). 
     Referring again to  FIGS. 4A and 4B , a seal  60  may be formed by a smooth section of the gas metering screw  31  and a smooth hole at the bottom of the threaded hole. The seal  60  is maintained in any selected position of the gas metering screw  31 . This seal  60  may prevent gas and/or debris carried by the gas from reaching the threading of the gas metering screw  31 . This may keep the threading clean so that the gas metering screw  31  does not seize up after prolonged use. In this example, the smooth hole at the bottom of the threaded hole has the minor diameter of the threads; however, in other examples the diameter of the smooth hole may be smaller than the minor diameter of the threads. This view also illustrates the interference fit of the mounting section of the spring pin  32 . 
       FIG. 6A  illustrates a front end view of the adjustable firearm gas block of  FIGS. 1-4B , and  FIG. 6B  illustrates a cross-sectional view taken along section line F of  FIG. 6A . Referring to  FIG. 6B , when the ingress port  35  is not completely covered, gas travels to the opening  62  where it may enter an opening of a gas tube (not shown) installed in the large hole  2 . The hole  1  ( FIG. 1 ) for pinning the gas tube is also shown in this view. 
       FIGS. 7A and 7B  illustrate a front view and an isometric view, respectively, of another embodiment similar in any respect to the adjustable firearm gas block described with reference to  FIGS. 4A-6B . In this embodiment, the head  41  of the spring pin  32  has no cut away (e.g., no pointed tip). The slope of the plurality of indentations on the head  41  of the gas metering screw  31  is shallower than the slope of the indentations in the embodiment described with reference to  FIGS. 4A-6B  (also each indentation is wider). This embodiment still provides one indentation every 45 degrees, but it may be possible and practical to provide more indentations (if desired) using the approach described with respect to the embodiment described with respect to  FIGS. 4A-6B . 
     It may be possible to keep the spring pin in a fully resting state when aligned with the indentations in either embodiment; however, this is not required. In other embodiments, the spring pin may apply less force to the gas metering screw in some rotational positions than other rotational positions. In either case, the adjustable firearm gas block still may give a user a clicking feedback associated with finite rotational positions between intermediary positions. 
     Any adjustable firearm gas block described herein may be used in the barrel assembly described with reference to  FIGS. 1-3 , or any known barrel assembly or later developed barrel assembly. Referring to  FIGS. 4A-6B , the adjustable firearm gas block may be manufactured without the timing boss for use with known barrel assemblies, e.g., mil spec barrel assemblies. Likewise, the barrel assembly described with reference to  FIGS. 1-3  may be manufactured with the adjustable firearm gas block features described herein, any other adjustable firearm gas block features known or later developed, or any other gas block features (such as on a standard non-adjustable firearm gas block). 
     Although various adjustable firearm gas blocks described with reference to  FIGS. 4A-7B  utilize a self-retaining spring pin, this is not required. Other embodiments may utilize some other structure with a section to make contact with the head of an adjustable firearm gas block. These pieces may protrude from the adjustable firearm gas block so that a position may be visually indicated to a user (in addition to any audible “clicking” indication provided by the structure moving into and out of indentations on the head of the gas metering screw). Other structures, self-retaining or otherwise, may be used to selectively release a force on a head of the gas metering screw at different rotational positions of the gas metering screw (the force is applied on the gas metering screw at intermediary rotational positions between the rotational positions). 
     Although various embodiments described with respect to  FIGS. 4A-7  are for an AR15, it should be appreciated that any of the adjustable gas block features illustrated or described herein may be used in any firearms having gas-operation systems (including direct impingement systems (which may use a gas tube similar to the gas tube described herein), piston-driven systems, and any other gas operation system now known or later developed). 
     Timing, Fastening, and Sealing Features for Firearm Gas Blocks 
     As explained earlier herein, a shoulder may be formed behind a location for a gas block by selectively removing material when the barrel is machined, and this shoulder fixes the position of the gas block in the lengthwise position. However, known shoulders do not prevent mis-timing the gas block (say, a wrong angular orientation in which gas flow is significantly impeded). 
       FIG. 8  illustrates an isometric view of another adjustable firearm gas block  800 , according to various embodiments.  FIG. 9A  illustrates a cross-sectional view of the adjustable firearm gas block  800  of  FIG. 8 , according to various embodiments.  FIG. 9B  illustrates a partial cross-sectional view taken along section line E of  FIG. 9A .  FIG. 9C  illustrates a cross-section view of the barrel  810  illustrated in  FIG. 9A  at a groove  921  on the barrel.  FIG. 9D  illustrates the tapered fastener  820  of the adjustable firearm gas block  800  of  FIG. 8 . 
     The adjustable firearm gas block  800  may include a timing system including a tapered fastener opening  821  and a tapered fastener  820  insertable in the tapered fastener opening  821 . This timing system rotationally orients the adjustable gas block  800  to position an ingress port of the gas block  800  over a gas port of the barrel (e.g., the gas port to supply gas from the barrel). 
     Referring to  FIG. 9C , which shows a cross section of the barrel  810  at the groove  921  on the barrel (with the tapered fastener  820  removed for clarity), the barrel  810  may define a groove  921 , which may be similar in any respects to any barrel-defined groove described in the &#39;399 publication. In this example, the groove  921  is a “V” slot. In other examples, a different slot may be provided, such as a rounded slot. 
     The tapered fastener  820  may be similar in any respect to any tapered fastener described in U.S. Patent Application Publication 2021/0231399, which is incorporated by reference herein. As illustrated in  FIG. 9D , the tapered fastener  820  includes four sections: a threaded section, a tapered section  932 , and a straight section proximate to each end (including small end  931 ). As the tapered fastener  820  starts to engage the groove  921  ( FIG. 9C ) the straight sections may prevent the tapered fastener  820  from being urged away from the barrel  810  ( FIG. 8 ). Specifically, the adjustable gas block  800  is arranged to form a hole of a corresponding diameter that the small end of the tapered faster  820  fits into and a counter bore with a corresponding diameter that the large end of the tapered faster  820  fits into (this can be seen in  FIG. 9A ). The tapered fastener  820  may be held into place on both sides of the taper lock interface  932  by these straight sections to keep either end of the tapered fastener  820  from moving away from the barrel  810 . 
     In other embodiments, a tapered fastener may not require the straight sections proximate to each end. A tapered fastener may include a single continuous taper with a first region having a taper lock interface to contact a taper interface of a barrel and a second region to contact a gas block. In other embodiments, a tapered fastener may have two distinct sections—a tapered first section to contact a taper interface of a barrel and a second non-tapered (or differently tapered) section to contact a gas block. 
     Referring again to  FIG. 9A , when the tapered fastener  820  is tightened (e.g., using a wrench tool in this example), the taper lock interface  932  ( FIG. 9D ) contacts a corresponding taper interface on the barrel  810 . In this example, the tapered fastener  820  includes threading to interface with an internal thread in the adjustable gas block  800 ; however, this is not required. In other examples, a tapered fastener may not include threads—it could be driven into the hole in the adjustable gas block device  800  to lockup with the taper lock interface provided on the barrel  810 . 
     The lockup of the interface  932  with the taper interface on the barrel is illustrated in  FIG. 9B . This lockup rotationally times the adjustable gas block  800  in the correct rotational position around the barrel  810 , which aligns the ingress port  965  of the adjustable gas block  800  to the gas port  935  of the barrel  810  without the use of a jig. The lockup also sealingly couples the adjustable gas block  800  to the barrel  810  by pulling the bore of the adjustable gas block  800  against a journal of the barrel  810 . 
     In this embodiment, the gas block  800  is adjustable—it includes a gas metering screw  831  (or some other rotationally actuated gas metering shaft), which may be similar in any respect to the gas metering screw  31  ( FIG. 4A ). However, the timing system illustrated in  FIG. 8  can be used in any gas block (whether adjustable or not). In one embodiment, the timing system illustrated in  FIG. 8  may be used with a gas block similar in any respect to the gas block  20  illustrated in  FIG. 1 . 
     Also, since the tapered fastener  820  serves two functions (e.g., timing and pulling the bore of a gas block against a journal of a barrel), the tapered fastener  820  may be used in gas blocks that may already include some other timing system (such as the timing system described with respect to  FIG. 1 ). Unlike some known gas block fasteners that may require thread locking compound to lock threading together, the tapered fastener  820  may be self-locking. The seal formed by this self-locking may not fail over as with other gas block fasteners that may require application of a thread locking compound to threading (this thread locking compound may fail over time due to the effects of barrel heating generated by operation of the firearm). A gas block using the tapered fastener  820  to pull the bore of a gas block against a journal of a barrel may transfer more gas from the barrel into the gas tube  975  than other gas blocks using other fasteners (which may leak gas initially, particularly due to complexity of installation, and over time due to the use of a thread locking compound). 
     In various embodiments, the bore of a gas block (to receive a rotationally drivable gas metering screw) may be arranged along an axis that is aligned with an axis of the bore of the barrel (e.g., parallel to or where the axes form an acute angle, i.e. where the axes are not perpendicular). The gas metering screw may include threading, however, it may be possible and practical to utilize other gas metering screws with any rotational interlock mechanism. 
     Referring again to  FIG. 9A , in this embodiment, a bore to receive the gas metering screw  831  may include a smooth section to form a seal with a non-threaded length of the gas metering screw  831 . This smooth section may be similar to any smooth section described herein, such as the smooth section described with respect to  FIGS. 4A to 4B . This smooth section may form a seal with the non-threaded length of the gas metering screw in any selectable position between maximum gas flow and minimum gas flow. As explained previously, this seal may prevent gas and/or debris carried by the gas from reaching the threading of the gas metering screw  831 . This may keep the threading clean so that the gas metering screw  831  does not seize up after prolonged use. 
     In the embodiment illustrated in  FIG. 9A , the gas metering screw  831  may also include a groove and one or more one or ring(s) in the groove to form the seal. Laminar gas sealing ring(s)  888  (e.g., metallic spiral retaining ring made from coiled flat wire) may be provided on the gas metering screw  831  to form a seal with the smooth section of the bore  960  in any selected position of the gas metering screw  831 . As explained previously, this seal may provide reliable operation of the gas metering screw  831 . In this example, the bore  960  below the thread hole has the minor diameter of the threads; however, in other examples the diameter of the bore  960  may be smaller than the minor diameter of the threads. 
     In various embodiments, any piston seals/rings (e.g., used for fluid sealing), now known or later developed, may be used in an adjustable firearm gas block similar to the interfacing between the laminar gas sealing ring(s)  888  and the bore  960 . For example, metallic split rings may be attached to the gas metering screw to interface with a groove in the gas metering screw to form a seal with the bore. It may be possible to use any seals/rings now know or later developed, for example a polymer seal configured to withstand the high temperatures of the gas expelled from the barrel. 
       FIG. 8  illustrates the adjustable firearm gas block  800  in the fully closed state.  FIG. 10  illustrates another cross-sectional view of the adjustable firearm gas block  800  in the fully open state, similar to  FIG. 6B . 
     Having described and illustrated various examples herein, it should be apparent that other examples may be modified in arrangement and detail. We claim all modifications and variations coming within the spirit and scope of the following claims.