SOUND-MODERATOR DEVICES FOR GUNS

Abstract: An gun-silencer (1) for mounting at the muzzle (9) of a gun-barrel comprises a baffle-free, generally-cylindrical gas-expansion chamber (2) intermediate a proximal entry-port (6) and a distal exit-port (7) both aligned with said gun-barrel when mounted thereon, the internal end walls of said expansion chamber being divergent from the entry-port at its proximal (3) end over a curve whose ends subtend an angle not greater than 90 DEG , and convergent on the exit-port (6) at its distal end (7) over a curve whose ends subtend an angle greater than 90 DEG .

Description: SOUND-MODERATOR DEVICES FOR GUNS This invention relates to sound-moderator devices for guns. Such devices are often loosely but colloquially referred to as "silencers", and that term will for convenience be used hereinafter, even though it will be appreciated that no such device however efficient can hope to succeed in wholly-annulling and therefore completely silencing the report (noise) inevitably generated by the discharge of a gun. And the term "gun" is used herein quite generically, to embrace all kinds of forced-ballistic projectile- dischargers, thus not only the kind of firearms employed for military and most sporting purposes (whether hand-held or otherwise, and irrespective of whether they are small-bore or large-bore weapons) but also other kinds operated by gases under compression, e.g. those colloquially known as "airguns", i.e. so-called air rifles and air-pistols. Silencers for guns have been proposed and used since early this century. The most successful over the intervening years have proved to be those known as the Maxim Silencer and the Unique Silencer, which are illustrated in the respective Figures A and B of the accompanying drawings. Both these classical designs of silencer are made to screw onto the muzzle of a gun, providing an enlarged chamber there into which the propulsive gases emergent from the muzzle can expand, and within which there are mounted usually-spiral baffles disposed either eccentrically or concentrically around the bullet path, which baffles engender gas-swirling or turbulent effects within the expansion chamber, that significantly dampen and attenuate the noise of the report. The fact that silencers of this classical, baffled-chamber design are still in use 80 or more years later testifies to their usefulness, but nevertheless they do have their limitations and disadvantages. Apart from the fact that still further reduction in - 2 - noise-level than they can achieve would be desirable, they have a particular drawback in that the baffles within the decompression- chamber are relatively fragile yet subject to intense temperature and mechanical stresses, so that they deteriorate with use and moreover need intermittent cleaning to remove deposits built-up thereupon during repeated use. As a generalization it would be fair to say that no silencer of this classical kind can be expected to remain serviceable beyond the passage therethrough of somewhere between say 200 and 2,000 rounds.... thus one could perhaps expect that both the chamber and the baffles would need cleaning every 200 rounds, while the baffles would need replacement every 2000 rounds. The intermittent cleaning of the chamber and/or replacement of the baffles is time-consuming, inconvenient and not inexpensive even when the silencer is used on single-shot weapons - while of course this consideration largely rules out the use of such silencers on "automatic" multi-shot weapons, where say 200 (or even 2,000) rounds can be expended rather quickly. There is therefore room for improvement in the classical baffled-chamber design of gun-silencer, and this invention springs from the discovery that excellent attenuation of the sound can be achieved by the adoption of a baffle-free but appropriately-shaped gas-expansion chamber, while the absence of baffles greatly improves the serviceable life of the silencer thus constructed. According to this invention there is provided a gun-silencer mountable at the muzzle of a gun barrel, said silencer comprising a baffle-free, generally-cylindrical gas-expansion chamber intermediate a proximal entry-port and a distal exit-port both aligned with said gun-barrel when mounted thereon, the internal end walls of said expansion chamber being divergent from the entry-port at its proximal end over a curve whose ends subtend an angle not greater - 3 - than 90°, and convergent on the exit-port at its distal end over a curve whose ends subtend an angle greater than 90° . While this invention is not to be limited by any theoretical considerations, it is currently believed that the superior results secured by its use can probably be explained upon the basis of some or all of the following hypotheses. When the bullet or other projectile leaves the gun-muzzle and enters the silencer-chamber through the entry-port therein, the propulsive gases in part follow the projectile, i.e. along the "bullet- path" (though under less pressure and therefore more slowly) but also to a considerable extent are allowed and indeed induced by the smoothly-curving and divergent entry-end walls of the chamber to preferentially follow its contours and thereafter continue along the generally-cylindrical intermediate-section walls of the chamber. The diverged gases are not defeated in that peripheral flow- path by the presence of any baffles, and consequently the flow of the gases along and adjacent to the chamber-walls is relatively non- turbulent and indeed thought to be at least quasi-laminar. This promotes maintenance of the "dead-space" which anyway always tends to follow a high-velocity projectile, helping to allow the projectile to reach and emerge from the silencer's exit-port fractionally ahead of its own still-maintained "dead-space". Thus the bullet or other projectile emerges from the silencer just ahead of the near-vacuum of its own "dead-space". The diverged, wall-following peripheral gases have a longer path to travel, and thus arrive at the exit-end fractionally after the bullet or other projectile, but in time to be there deflected by the smoothly-curved and slightly-re-entrant exit-end walls back into the dead-space behind the projectile. It is this which is currently believed to dampen the sound of the report, for two reasons - firstly that the dead-space is effectively a vacuum through which sound - 4 - cannot travel, while secondly the dead-space allows the peripheral gas-flow, now backwardly-directed, to implode into "dead-space" and to a major extent thereby annul what would otherwise be the noise of the report. Whether that explanation is correct or not, it has been empirically determined that the gun-silencer of this invention is highly-effective in moderating the sound of the weapon's report, and on the evidence so far is remarkably free (as indeed one would expect) from the maintenance requirements and baffle-replacement problems long associated with the classical baffled-chamber designs... as well as indeed displaying other advantages, as will emerge subsequently. The gun-silencer will normally include means at its proximal end for detachable mounting, upon a gun-barrel to which it is to be fitted, with its entry- and exit-ports aligned in communication with the muzzle of said gun-barrel. The divergent curve at the proximal end will desirably be a substantially circular arc subtending an angle of 75 - 90°. This may be compared and contrasted with the fact that the convergent curve at the distal end will advantageously be a substantially circular arc subtending an angle of at least 100°. At the practical level, both for convenience and economy of manufacture as well as for facilitating cleaning and maintenance during use, the gun-silencer will preferably be so constructed and arranged that at least one end-wall thereof can be detached from and re-attached to the generally-cylindrical side-walls of the gas- expansion chamber thereby providing easy access to said chamber. It is in fact best if the silencer is so constructed and arranged that both the proximal and distal end-walls can be detached and re- attached to the side-walls. - 5 - Such detachment and re-attachment can be most readily effected via screw-threaded inter-engagement between the respective end-wall and the side-walls. In that case the screw- threaded inter-engagement can most conveniently be provided at the point at which the respective curved end-wall merges or demerges flush with the intermediate side-walls. In any event, a sealing ring will very desirably be interposed between the inter- engaged end-wall(s) and side-walls so as to establish a gas-tight seal therebetween. According to a further feature of this invention there is also provided a silenced gun, comprising a gun-silencer as herein disclosed, mounted at the muzzle of the gun-barrel with its entry- and exit-ports aligned with said barrel. In order that the invention may be well understood, it will now be described in further detail, though only by way of illustration, with reference to the accompanying drawings, in which: Figures A and B, which are included only for purposes of comparison, are diagrammatic depictions of the classical structures of conventional gun silencers, thus: Figure A is a depiction of the Model 1910 "Maxim" Silencer; and Figure B is a depiction of the "Unique" Silencer system. Briefly described, the Maxim Silencer of Figure A has a cylindrical expansion chamber a around a non-axial bullet-path b passing between an entry-port c and an exit-port d, the ports and thus the bullet-path being arranged parallel to but offset from the axis of the expansion chamber. Within the expansion chamber a there are disposed a series of spiral baffles e, §__ and so on, all of them eccentrically-apertured to surround the bullet-path, and arranged and held in proper alignment by grooves (not shown) within the expansion chamber. - 6 - And the Unique Silencer of Figure B again has an expansion chamber a around a bullet-path b_, (which however here is axial of the chamber) passing between an entry-port c and an exit-port d. Likewise there are within the expansion chamber a series of baffles, which however here comprise successive sections of spiral spring £ £ and so on, interposed between successive centrally-apertured washers g_, g and so on. Those classical constructions of gun-silencer can be contrasted with the gun-silencer of the present invention, illustrated in Figures 1 to 4, in which: Figure 1 is an axial cross-sectional view through a preferred embodiment of silencer for use with a small-bore firearm; Figure 2 is a similar axial cross-sectional view though the same embodiment when mounted on the muzzle of a firearm, and at a moment when a bullet fired from the gun is leaving the gun- muzzle and entering the expansion chamber of the silencer through its bullet-entry port; Figure 3 is a similar axial cross-sectional view through the same muzzle-mounted embodiment, but at a subsequent moment when the bullet has already entered the expansion chamber and is midway between the bullet-entry and bullet-exit ports of the silencer chamber; Figure 4 is also a similar cross-sectional view through the same muzzle-mounted embodiment, but now at a still-later moment when the bullet is just leaving the exit-port from the silencer chamber. Referring first to Figure 1 , the sound-moderator device or "silencer" generally indicated 1 comprises a baffle-free gas- expansion chamber 2 between a bullet-entry end-wall 3 and a bullet-exit end-wall 4, said end-walls 3 and 4 being interconnected by generally-cylindrical intermediate side-walls 5. - 7 - The bullet-entry or "proximal" end-wall 3 is provided with an entry-port 6, aligned and concentric with the axis of the cylindrical intermediate side-walls 5, that axis defining the bullet-path, and the bullet-exit or "distal" end-wall 4 is similarly provided with a bullet- exit port 7, which again is aligned and concentric with the axis of the cylindrical intermediate side-walls 5 and thus the bullet-path. The bullet-entry port 6 is internally screw-threaded at 8, and (now see Figures 2-4) correspondingly the gun-muzzle is externally screw-threaded, so that the gun-silencer 1 and the gun-muzzle can be threadedly interengaged as shown at 9. Bullet-entry end-wall 3, at its distal end remote from the entry-port 6, is internally screw-threaded; and the proximal end of intermediate side-walls 5 are externally screw-threaded, so that the end-wall 3 and side-walls 5 can be threadedly-interengaged as shown at 10. The threaded-engagement between end-piece 3 and intermediate section 5 is rendered gas-proof by interposition therebetween of sealing ring 1 1. Similarly, the distal end of intermediate side-walls 5 is externally screw-threaded; and the proximal end of bullet-exit end- wall 4 is internally screw-threaded, so that the end-wall 4 and side- walls 5 can be threadedly-interengaged as shown at 12. Here again, this threaded interengagement 12 is rendered gas-proof by interposition of a sealing ring 13. It will be noted that the gas-expansion chamber is baffle-free, and that the internal walls of bullet-entry end-piece 3 diverge arcuately from entry-port 6 to merge flush with the internal walls of intermediate section 5. The ends of that arc subtend an angle of 90° or (dependent on the angle at which the arcuate wall departs from the entry-port 6) less. That however may be contrasted with the bullet-exit end-wall 4 at the distal end of intermediate sidewalls 5, where the internal - 8 - contour of end-wall 4 again is arcuate, but in this case after demerging flush with the internal contour of intermediate side-walls 5 then converges arcuately towards the bullet-exit port 7 over an arc the ends of which subtend an angle greater than 90°, so that the chamber-end of exit-port 7 provides a sort of "lip" which stands proud of the general plane of that distal end of the gas-expansion chamber 2. Referring now more particularly to Figures 2 to 4, these illustrate successive stages in the passage of a bullet through the silencer of Figure 1 , and an explanation is offered below of what is currently believed to be the modus operandi of the silencer, though it is to be understood that this explanation is put forward as an hypothesis and without intending to limit the scope of the invention. Figure 2 illustrates the silencer as a bullet 20 leaves the gun- muzzle 9 and enters the expansion chamber 2, followed by the propulsive gases 21 which as the bullet 20 is emergent from the gun muzzle 9 diverge towards the sides of chamber 3 along the direction of arrows 21 ' and 21 ". Figure 3 illustrates the silencer a fraction later, showing the bullet 20 in mid-chamber, followed more slowly by some of the axially-flowing propulsive gases 21 '", and parting the gases already within the chamber in a "slipstream" in the direction of arrows 22' and 22" towards the side-walls 5. Meanwhile the diverged explosion gases 21 ' and 21 " have followed the internal contour of proximal end-wall 3 and are passing in quasi-laminar flow along and adjacent to side-walls 5, but behind the bullet 20 - which is followed more slowly by some of the axially-flowing propulsive gases 21 '" but leaving behind it a "dead space" 23. Figure 4 shows the moment at which the bullet 20 emerges from the exit-port 7, with its dead space 23 to be found in and/or adjacent that exit-port, and followed of course by the slow-moving - 9 - axial-flow gases 21 '", but with the peripheral-flow gases 21 ' and 21 " now diverted towards the exit-port 7 and indeed deflected by the reentrant curve on end-wall 4 backwardly towards and into the dead space 23. This is what currently is supposed to happen, and it is assumed that the implosion of the peripherally-flowing gases 21 ' and 21 " into the tail-end of the dead space 23, coupled perhaps with the sound-barrier created by the dead space adjacent and/or within the exit-port 7, result in the sound-deadening effect achieved by the gun silencer of this invention. But whether that explanation is correct or not, it is an empirically-determined fact that the gun silencer of this construction is highly effective in a variety of ways. In tests, conducted by professionally-competent experts, it has been found that: - the sound signature of the weapon was drastically reduced (as compared with conventional silencers) while using high-velocity ammunition; - disturbance of camouflage and/or dust normally caused by muzzle-blast was apparently eliminated, being imperceptible when observed up to 1 metre in front of the muzzle; - less barrel-whip occurred than when using the classical types of silencer, resulting in greater accuracy over ranges of temperature fluctuation; and - when using low-velocity ammunition, the possibility of identification of the firing position is largely eliminated. And indeed it appears that with the prototype silencers in accordance with this invention so far produced and tested, there is as compared with the classical silencer designs a great reduction in the sound emitted, substantially complete elimination of muzzle - 10 - blast and muzzle flash, apparently a significant reduction in muzzle flip and even indeed a perceptible reduction in weapon-recoil.

Claims: - 11 - CLAIMS 1. A gun-silencer (1 ) mountable at the muzzle of a gun barrel, said silencer comprising a baffle-free, generally-cylindrical gas- expansion chamber (2) intermediate a proximal entry-port (6) and a distal exit-port (7) both aligned with said gun-barrel when mounted thereon, the internal end walls of said expansion chamber being divergent from the entry-port at its proximal (3) end over a curve whose ends subtend an angle not greater than 90°, and convergent on the exit-port (6) at its distal end (7) over a curve whose ends subtend an angle greater than 90°. 2. A gun-silencer as claimed in claim 1 , which includes means (8) at its proximal end (3) for detachable mounting upon a gun-barrel (9) to which it is to be fitted, with its entry- and exit-ports (6 and 7) aligned in communication with the muzzle of said gun-barrel. 3. A gun-silencer as claimed in claim 1 or claim 2, in which the divergent curve at the proximal end (3) is a substantially circular arc subtending an angle of 75 - 90°. 4. A gun-silencer as claimed in any of claims 1 to 3, in which the convergent curve at the distal end (4) is a substantially circular arc subtending an angle of at least 100°. 5. A multi-part gun-silencer as claimed in any of the preceding claims, so constructed and arranged that at least one end-wall (3 and/or 4) thereof can be detached from and reattached to the generally-cylindrical side-walls (5) of the gas-expansion chamber (2) thereby facilitating access to said chamber. 6. A multi-part gun-silencer as claimed in claim 5, so constructed and arranged that both the proximal and distal end-walls (3, 4) can be detached and reattached to the side-walls (5). 7. A multi-part gun-silencer as claimed in claim 5 or claim 6, in which detachment and reattachment can be effected via screw- - 12 - threaded inter-engagement between the respective end-wall (3 and/or 4) and the side-walls (5). 8. A multi-part gun silencer as claimed in claim 7, in which the screw-threaded inter-engagement is provided at the point at which the respective curved end-wall (3 and/or 4) merges or demerges flush with the intermediate side-walls (5). 9. A multi-part gun silencer as claimed in claim 7 or claim 8, in which a sealing ring (10 and/or 13) is interposed between the inter- engaged end-wall(s) (3 and/or 4) and side-walls (5) to establish a gas-tight seal therebetween. 10. A silenced gun comprising a gun-silencer as claimed in any of the preceding claims mounted at the muzzle (9) of a gun-barrel with its entry- and exit-ports (6 and 7) aligned with said barrel.

Inventors: LAPWOOD GERALD, LAPWOOD, GERALD
Applicants: LAPWOOD GERALD, LAPWOOD, GERALD
Application year: 1999
Main classification: F41A21
IPC codes: F41A21