Gun muzzle brake

A concave surface at the front end of a gun facing the gun muzzle is tilted upwardly to redirect propelling gas rays to a venting port or ports adjacent the gun muzzle for virtual recoil neutralization. In the case of a single port at the top of the expansion chamber, not only axial recoil but also vertical recoil are virtually neutralized. In a dual-port arrangement, two ports (one on each side of a vertical plane through the axis of the expansion chamber) are provided with two concave surfaces tilted upwardly and outwardly to separately redirect rays of propellant gas through each of the two ports which are positioned with the extent of the area of each port above a horizontal plane through the axis of the expansion chamber determined empirically to provide neutralization of both vertical and horizontal recoil as well as axial recoil. Each concave surface for the dual-port arrangement is thus tilted up and to one side of the expansion chamber axis.

FIELD OF THE INVENTION 
The invention relates to a muzzle brake adapted to be axially secured to 
the muzzle of a gun of large or small caliber. 
BACKGROUND OF THE INVENTION 
The recoil of a gun severely interferes with the accuracy of firing at a 
target, particularly when using hand-held guns under rapid fire 
conditions, because the recoil of the gun tends to cause the muzzle to 
kick in a direction that depends largely upon the configuration of its 
stock, i.e., the wooden or metal part below the axis of the barrel. For 
example, a ground mobile antiaircraft or antitank gun will tend to kick 
up, lifting the gun carriage off the ground and thus cause it to change 
position in azimuth and/or elevation. Similarly, a hand-held gun, such as 
a pistol or rifle, will tend to kick up and often to one side, generally 
to the side away from the person holding the gun, making rapid 
semiautomatic fire at a target with accuracy of all but the first round 
impossible. Consequently, it is common practice to use two hands on the 
gun, including a pistol, but it is seldom that the person firing the gun 
is capable of absorbing the recoil equally in both arms, particularly a 
pistol, and so the gun will tend to kick to one side, even in the case of 
a rifle, unless held with the aid of some sturdy support to stabilize the 
gun barrel during recoil, not only because of the stock configuration but 
also because of the unsymmetrical disposition of the person's body 
relative to the gun. In an automatic weapon, this recoil problem is more 
severe since the barrel will kick incrementally with each firing cycle 
causing the gun to "walk" up and away from the target. 
To overcome this recoil problem, attempts have been made for many years to 
provide a muzzle brake having an expansion chamber with a front annular 
surface or shoulder that is orthogonal to the muzzle axis to reverse the 
direction of expanding propellant gases and venting the gases through 
ports inclined rearwardly and outwardly as shown in U.S. Pat. No. 
2,212,683, and possibly with similar ports ahead of the recoil controlling 
ports but inclined forwardly and upwardly to exhaust some expanding gases 
before they are reversed in direction to deflect propellant gases from 
ports that are reversed in direction away from the person firing the gun, 
as shown in U.S. Pat. Nos. 2,212,684, '685 and '686. See also U.S. Pat. 
Nos. 2,953,972, 4,811,648 and 4,852,460. 
More complex arrangements have been developed for muzzle brakes in an 
attempt to stabilize the muzzle of a firearm and minimize the blast of 
reversed propellant gases against the person firing the gun, such as a 
muzzle brake having two expansion chambers with ports, a first expansion 
chamber with forwardly and upwardly directed ports and a second larger 
expansion chamber with a conical forward port at the front end for 
deflecting gases up through large upwardly directed slots orthogonal to 
the muzzle axis, as shown in U.S. Pat. No. 4,879,942. Another complex 
arrangement is shown in U.S. Pat. No. 4,930,396 comprising a series of 
tapered sections, each section having rings (annular rows) with ports 
having their axes orthogonal to the muzzle axis. U.S. Pat. No. 4,945,812 
discloses a similar arrangement of multiple rings of ports but without the 
series of tapered sections. Instead, that arrangement relies upon ports in 
each ring (annular row) to form baffles that reduce recoil by directing 
propellant gases radially out through the ports. 
An even more complex arrangement comprises a "flash hider" having a 
threaded bore that accepts the gun barrel at one end and a muzzle brake at 
the other. The end of the muzzle brake is screwed into the "flash hider" 
leaving a cavity between it and the gun muzzle, thus providing a small 
expansion chamber the forward end of which is an annular surface 
orthogonal to the muzzle axis. Five "retrojet channels" (ports) through 
the wall of the "flash hider" are inclined upwardly and rearwardly to 
reduce recoil and inhibit transverse movement of the gun muzzle, one at 
the top in a vertical plane, one on either side of the top, one in a plane 
60.degree. from the vertical, and another one on either side of the top 
one in a plane 120.degree. from the vertical. The net effect of all 
retrojet channels at the rear of the muzzle brake is a rearwardly and 
downwardly directed force. In addition to that, the muzzle brake also has 
a "void" which forms a larger expansion chamber with a sloped face within 
the flash hider to direct expanding gases upwardly and rearwardly through 
elongated slots to counteract the natural tendency of the gun muzzle to 
kick upwardly and laterally. 
Yet another prior-art arrangement shown in U.S. Pat. No. 5,225,615 
comprises a gun barrel shroud having chamber in front of the gun muzzle 
with an inner diameter equal to the outer diameter of the gun barrel. The 
forward end of the chamber is capped by a disc having an exit orifice for 
the gun projectile to force expanding propellant gases to escape close to 
the capping disc through upwardly and rearwardly slanted (or slightly 
forwardly slanted) slots. Such an arrangement would be more suitable for 
guns of small caliber that exhibit less recoil but which still require 
some force to compensate the tendency of the gun to "walk" up under rapid 
firing conditions. 
An objective of this invention is to provide an improved arrangement for a 
muzzle brake suitable for firearms of large and small caliber that not 
only neutralizes the tendency of the muzzle to kick back but also 
neutralizes any recoil forces that may cause the gun muzzle to kick 
upwardly and laterally. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a muzzle brake is provided as a 
coaxial extension of a gun barrel comprising a housing affixed to the end 
of the gun barrel. The housing has a gas expansion chamber with a concave 
rearward facing surface and at least one port through a sidewall for 
venting expanding projectile propelling gases. The concave surface is 
preferably a segment, i.e., is ideally shaped to be a precise segment of a 
sphere, or at least approximately shaped to be a segment of a sphere 
having a radial axis normal to the segmenting plane tilted upwardly such 
that the radial center of the segment is at a point within the expansion 
chamber that is ideally or at least approximately equidistant from the 
center of the gun muzzle and the center of the exhaust port in the wall of 
the expansion chamber. 
In the case of a single venting port, the port is centered at the top of 
the expansion chamber in order to neutralize both the recoil and the 
upward kick of the gun barrel, i.e., to neutralize both the backward and 
upward forces on the gun barrel at the muzzle, as well as any lateral 
forces of the gun barrel. 
In the case of dual exhaust ports, one on each side of a vertical plane 
through the muzzle brake axis, the forward end of the expansion chamber is 
provided with dual concave rearward facing surfaces, one on either side of 
the vertical plane passing through the muzzle brake axis, each surface 
being a segment of a hemisphere having a radial axis normal to the 
segmenting plane tilted upwardly and outwardly such that the radial center 
of the segment is at a point within the expansion chamber equidistant from 
the center of the gun muzzle and the center of the venting port on the 
same side of a vertical plane through the muzzle brake. The centers of the 
ports are spaced equally from the vertical plane at a selected angle from 
the vertical plane approximately equal to 90.degree..+-..increment., where 
the sign and magnitude of .increment. is determined empirically for the 
particular gun to be equipped with the muzzle brake. The radial centers of 
the dual spherical segments are at points within the expansion chamber 
that are equidistant from the center of the gun muzzle and the centers of 
the venting ports on the same side of the vertical plane through the 
muzzle brake axis as the spherical segments, thereby neutralizing axial 
recoil forces of the gun barrel as well as both lateral and vertical 
forces on the gun barrel. 
In the case of more than two exhaust ports, a spherical surface is provided 
for each port that is ideally the shape of a segment of a sphere with its 
radial center equidistant to the center of the muzzle and the center of 
the exhaust port to which the spherical center is to redirect propelling 
gases, such as three venting ports, one venting port centered at the top 
of the expansion chamber and two venting ports spaced at equal angles from 
a vertical plane through the muzzle brake axis. 
More than three exhaust ports may be similarly provided. For example, many 
exhaust ports may be spaced completely around the expansion chamber in a 
ring, or even in two or more rings with venting ports in each ring 
displaced relative to any adjacent ring to space the centers of the 
venting ports even with webs between venting ports of any adjacent rings. 
That arrangement provides equidistant spacing between any three adjacent 
ports of the rings everywhere around the axis of the muzzle brake. In that 
case, the concave surface may, in practice, be provided as an annular 
concave surface having a cross section in every plane passing 
perpendicularly through the axis of the muzzle brake that is a segment of 
a circle the radial center of which is positioned equidistant from the 
center of the gun muzzle and the average center of the ports in the cross 
section of the annular concave surface. 
The novel features that are considered characteristic of this invention are 
set forth with particularity in the appended claims. The invention will 
best be understood from the following description when read in connection 
with the accompanying drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS 
In the first embodiment of the invention illustrated in FIGS. 1a through 
1h, the main propulsion gas from a gun barrel 10 (shown in FIG. 1h) 
strikes a concave baffling surface 11 in an expansion chamber 12 of the 
muzzle brake 13 coaxially secured by machined threads 14 on the end of the 
gun barrel in order to deflect the propulsion gases back toward a port 15 
in the wall of the expansion chamber, thereby producing a forward reaction 
force approximately equal to the recoil of the gun discharge when it is 
fired. The concave baffle 11 is ideally formed by machining a segment of a 
spherical surface in an end disk 16 having a bore 17 aligned with the axis 
of the gun barrel 10 as shown in FIG. 1h. The end disk 16 is machined 
separately, then combined as shown in FIG. 1g and welded to the muzzle 
brake 13 as shown in FIG. 1d. To machine the concave surface 11, the end 
disk 16 is fixed in the machining mill such that the radial center 18 of 
the spherical segment to be formed is at a point that will lie within the 
expansion chamber 12 and is equidistant (d.sub.1 =d.sub.2) from the center 
C.sub.1 of the gun muzzle (the end of the gun barrel 10) and the center 
C.sub.2 of the venting port 15 in the wall of the expansion chamber 12. 
The concave surface 11 will then reflect propulsion gases from the gun 
muzzle to the venting port 15, as shown in FIG. 1h for gases expanding 
from the center C.sub.1 of the muzzle along two possible lines for the 
reflected gases to converge at the center C.sub.2 of the port. 
It is recognized that propulsion gases may begin expanding from other 
points further into the gun barrel 14 and from points off the gun barrel 
or muzzle axis 19 so that it should be understood that the two rays of 
propulsion gases shown in FIG. 1h are intended to be illustrative and not 
definitive; reflected rays from the other points in the muzzle and further 
back into the gun barrel would be incident on the concave surface at other 
points and be reflected along different paths to emerge from the port at 
different points, but the main port of the expanding propulsion gas energy 
will pass through the port which is extended over almost half of the 
cylindrical wall of the expansion chamber and centered at the top. 
The propulsion gases not reflected by the concave surface 11 are then 
directed to the atmosphere through a porting system comprising one or more 
ports in the disk 16, such as a single port 20 centered on a vertical 
plane passing through the muzzle brake axis, or dual ports, one to each 
side of the vertical plane that are centered on or slightly above a 
horizontal plane passing through the muzzle axis, as shown for the second 
embodiment in FIGS. 2a and 2c. As expanding and reflected gas rays reach 
the area adjacent to the port 15, they are intersected by newly emerging 
main discharge gas rays from the gun muzzle, but these will merely enhance 
the venting of propulsion gases with greater velocity since the emerging 
rays will have more energy than the reflected rays. 
The force of the main discharge gases that have been reflected by the 
concave surface 11 in the expansion chamber 12 impart a certain amount of 
forward and downward energy to the barrel of the gun, the downward force 
on the barrel depending on the radius of the spherical segment formed for 
the concave surface 11 and the position of the sphere center. In that 
manner, the initial recoil generated by the propulsion gases accelerating 
a projectile down the bore of the gun barrel are counteracted by the 
propulsion gas rays reflected by the concave surface 11 thus neutralizing 
axial recoil thrust. Since these rays are reflected rearwardly and 
upwardly, there is a portion of the propulsion gas energy that is used to 
apply a downward force on the end of the gun, thus neutralizing the 
upwardly directed force of the axial recoil thrust that tends to cause the 
gun barrel to kick or rise up when the gun is fired. The port must have an 
area adequate to vent the combined deflected gases and emerging main 
propelling gases. 
In the case of dual venting ports 15a and 15b illustrated in FIGS. 2a 
through 2d, the concave surface 11 of the first embodiment comprises two 
concave surfaces 11a and 11b at the front end of the muzzle brake 
expansion chamber 12. The two venting ports are located at the rear of the 
expansion chamber. Each concave surface is ideally shaped as a segment of 
a spherical surface with its radial axis at a point 18' equidistant 
(d.sub.1 =d.sub.2) to the center C.sub.1 of the gun muzzle and the center 
C.sub.2 of the venting port on the same side of a vertical plane through 
the barrel and muzzle brake axis 19. 
This dual-faced (concave) surface 11' (comprising concave surfaces 11a and 
11b) is inclined from the vertical (tilted up) so that the top edge of the 
surfaces 11a and 11b are further from the gun muzzle than the bottom edge 
as shown in FIG. 2c to assure impinging propulsion gases are reflected at 
a positive angle with respect to a horizontal plane. The main propulsion 
gas rays striking the inclined dual-faced surface 11' imparts a downward 
force on the muzzle as well as a forward force in a manner similar to the 
single port muzzle brake of FIGS. 1a through 1h but with two ports 15a and 
15b, the extent to which a downward force is imparted on the gun barrel 
may be empirically designed by simply adjusting the centers of the ports 
15a and 15b up or down equally and machining the concave surfaces 11a and 
11b in the same manner as before, resulting in the concave surfaces being 
tilted up more the further the port centers are moved up, i.e., the higher 
the port centers are above a horizontal plane through the axis 19 of the 
muzzle brake. In that manner, the gases deflected by the dual-faced 
surface 11' are directed rearwardly and upwardly on each side of a 
vertical plane through the axis 19. The reflected gas rays combine with 
the following emerging main propulsion gas rays and are deflected in a 
direction almost orthogonal to the gun muzzle axis and at an upward angle 
from a horizontal plane through the muzzle brake axis. 
The venting system for such a dual-faced surface 11' has a hole at either 
side of the expansion chamber with the rearward edges thereof near the gun 
muzzle. The ports are disposed on the sides of the main chamber and 
centered on or slightly above a horizontal plane passing through the axis 
of the muzzle. The ports must have an area adequate to vent the combined 
deflected gases and emerging main discharge gases. 
In an extension of the present invention beyond dual ports, such as three 
ports by combining the single port with the dual port arrangement, the 
spherical baffling surface for the top venting port 15 would first be 
machined. The spherical surfaces for side venting ports 15a and 15b would 
then be machined by simply reorienting the cutting tool, first to one side 
and then to the other. A fourth venting port opposite the top port 15 
could also be added. In that case, the baffling surface for the fourth 
port would be machined last. The baffling surfaces for the ports 15, 15a 
and 15b would be tilted as before. However, by adding a bottom port, the 
effect of neutralizing the tendency of the muzzle to kick upwardly is 
greatly reduced if not virtually canceled. However, by moving the centers 
of the side ports 15a and 15b further up from a horizontal plane through 
the muzzle brake axis, some of that neutralizing effect on forces that may 
cause the gun muzzle to kick upwardly and laterally may be retained, if 
desired, while maintaining the top port 15 and the opposite (fourth) port 
centered on a vertical plane through the muzzle brake axis. 
A number of ports greater than 3 or 4 may be similarly provided around the 
expansion chamber as shown in FIG. 3. The sizes of the venting ports must 
necessarily be adjusted to leave sufficient web between ports to support 
the disk on which the spherical baffling surfaces are cut. To accomplish 
the machining of the baffling surfaces for a large number of venting ports 
significantly greater than 3 or 4, the resulting concave surfaces machined 
on the end disk 16 will approach an annular concave surface 11 in which 
case the orientation of the cutting tool would remain the same while the 
end disk 16 being cut is gradually rotated about its axis. By continuing 
to machine the concave surface through at least one full rotation of the 
disk 16, the result is an annular concave surface which at every radial 
cross section will have a spherical shape with the radial center between 
the muzzle center and the expansion chamber wall and equidistant from the 
muzzle center and a line through the average center of the ports. 
Thus, after so cutting the annular concave surfaces while the end disk is 
turned on its axis, it will have an annular surface that is the shape of a 
true spherical segment at every radial cross section with the radial 
center of the segments at a point within the expansion chamber that is 
equidistant from the center of the gun muzzle and an annular line passing 
through the center of the ports in the center ring if the number of rings 
is odd and between the two center rings if the number of rings is even. 
While it would be possible to place a single ring of rectangular ports 
around the expansion chamber next to the muzzle for optimum port venting 
and greater strength of the web between the ports, the ring of ports may 
consist of a first ring of smaller circular ports and two additional rings 
of circular ports with their centers offset as shown in FIG. 3. In 
practice, circular ports of smaller diameter may be used by adding 
additional rings of ports, such as a fourth and fifth. The annular line 
through the centers of the ports in the center ring in the case of an odd 
number of rings (or through the center of the web between the central two 
rings in the case of an even number of rings) will then be the "center of 
the port" at a cross section taken anywhere in a radial plane passing 
through the muzzle brake axis. The result is a muzzle brake in which the 
reaction of propulsion impinging gases against the baffling surface will 
neutralize virtually all of the recoil of the gun, and any tendency of the 
muzzle to kick upwardly and laterally will be minimized to the point where 
the person firing the gun will likely be able to hold the gun aimed on the 
target from round to round, even with an automatic weapon. 
Thus, the baffling surface for a multiplicity of venting ports in a ring or 
rings may comprise an annular concave surface inscribed with its radial 
center at a point between the center of the gun muzzle and the average 
center of the venting ports. At every radial cross section, the concave 
surface is tilted out away from the muzzle axis to direct deflected 
propulsion gases rearwardly and outwardly. The porting system is located 
on the wall of the expansion chamber proximate the muzzle. 
Theory and Design 
The length and width of the muzzle brake body and the location and width of 
the venting port system are determined by several factors: 
The amount of recoil reduction desired is determined by the surface area of 
the formed baffle, which is limited by dimensions of the body. 
The length of the bullet and the length of the portion of the bullet that 
has a full diameter profile. 
The bullet and gas velocities. 
The theory of design of the muzzle brake is as follows: As the projectile 
emerges from the end of the gun muzzle and enters the body of the muzzle 
brake, the main discharge gas which has a greater velocity than the 
projectile velocity begins to overtake the projectile. Before the main 
discharge gas passes the projectile, the projectile blocks the centrally 
located bore in the formed baffling surface. For optimum performance, the 
projectile should begin to block the centrally located bore at the time 
that the main discharge gas reaches the forward part of the cylindrical 
section of the projectile. The pressure continues to increase during the 
time that the centrally located port is blocked by the projectile. 
The longer the duration in time that the high pressure of the main 
discharge gas exerts a force on the formed baffle, the greater is the 
forward force exerted on the formed baffling surface by the gas to 
neutralize recoil. The formed baffling surface is shaped so that the main 
discharge gas striking the formed baffling surface is deflected rearwardly 
toward the port venting system. The energy level of the deflected gas is 
considerably less than the energy level of the main discharge gas. The 
deflected gas is intersected by the outward expanding, newly emerging, 
main discharge gas, and the two combine to exit the body through the port 
system in a direction approximately perpendicular to the muzzle axis. 
The location of the forward part of the port system is determined by the 
dispersion of the main discharge gas from the gun muzzle. The sound power 
level (SPL) measurements and shadow graph pictures taken at various 
positions, with the position directly in front of the muzzle being 
designated 0.degree. and the position normal to the muzzle axis being 
designated 90.degree., indicate the following: the sound and gas patterns 
are quasi-spherical with the intensity at 90.degree. being one half the 
intensity at 0.degree.. It is assumed that the intensity at 45.degree. 
would be three quarters the intensity at 0.degree.. The forward part of 
the port venting system must be positioned close enough to the gun muzzle 
so that a major portion of the main propellant gas is directed towards the 
formed baffling surface and not into the atmosphere through the port 
venting system. The greater the length of the projectile the longer the 
distance that the forward section of the port venting system can be from 
the gun muzzle. The port venting system must be long enough to allow the 
deflected gases and the newly emerging main discharge gases to combine and 
exit the expansion chamber. 
The formed baffling surface must be positioned close enough to the gun 
muzzle so that the high energy component of the main discharge gas 
impinges directly on the formed baffling surface and is not bounced from 
the side of the body onto the baffling surface at so great an angle that 
the flow pattern from the formed baffling surface is distorted and the 
deflected gas is not directed to the port venting system. 
The desired gas flow pattern for maximum efficiency is such that the high 
energy component of the main propellant gas ray exerts a forward force 
when it strikes the formed baffling surface, and the deflected gas ray is 
directed towards the port system where it is intersected by the newly 
emerging main discharge gas ray. The two intersecting gas rays combine and 
the resulting ray is directed to the atmosphere through the port venting 
system while the newly emerging main propellant gas flow continues to 
exert a forward force on the formed baffling surface until the following 
emerging main gas energy drops to near zero. 
In summary, a muzzle brake is provided with a cylindrical expansion chamber 
having a concave surface at the front end facing the muzzle and tilted 
upwardly to redirect propelling gas rays to a venting port or ports 
adjacent the muzzle. In a single venting port arrangement, the port at the 
top of the expansion chamber not only allows for axial recoil to be 
neutralized but also any vertical and horizontal forces on the muzzle due 
to recoil. In a dual-port arrangement, two ports (one on each side of the 
expansion chamber) are placed with their centers equally spaced above a 
central horizontal plane, and a concave surface is provided for each port 
to redirect rays of propellant gas through the dual ports. Each concave 
surface is tilted up and to one side of a central vertical plane. An 
arrangement of three ports may be provided by combining the single port 
arrangement with a dual-port arrangement, each port with its own tilted 
concave surface on a portion of a front end disk, and an arrangement of 
four ports may be provided by combining a fourth port (with its own 
concave surface) at the bottom opposite the top port. 
To enhance recoil neutralization, the position of the dual ports on the 
sides may be empirically determined to optimize neutralization of any 
vertical and horizontal forces on the muzzle due to recoil. For maximum 
neutralization of recoil, a multiplicity of ports may be provided in a 
ring or rings near the muzzle, in which case the concave surfaces provided 
for redirecting rays of propellant gas through the ports approaches an 
annular concave surface with the same shape at every radial cross section 
not unlike that for each of the dual ports, except that each of the dual 
ports would become one of a succession of overlapping groups of smaller 
offset ports or one of a succession of overlapping clusters of smaller 
offset ports in a ring (annular band) around the expansion chamber.