Wad for shotgun shotshell

A wad for a shotgun shotshell with a crimped case, comprising a seal member located adjacent to a propellant in the case and a rotor opposed to the seal member. The seal member and the rotor are interconnected for relative sliding and rotation and have opposed end faces. The seal member has at least one explosion gas passage hole. The rotor has, on the end face opposed to the seal member, gas jet grooves which are spaced from the axis and which extend in a predetermined direction to be connected to the outer periphery of the rotor and to the hole of the seal member. The rotor has blades or male-female connectors for transmitting the rotation of the rotor to a projectile in the case.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a wad for a shotgun shotshell, which can be used, 
for example, with a sporting gun. 
2. Description of the Prior Art 
A shotshell for a shotgun for hunting or a shooting match has a case with a 
primer. In the case, powder (propellant), a wad, and a projectile, such as 
shot (below, "pellets") or a slug, are charged. The case is provided, on 
its front end, with a crimp for preventing the projectile from coming out 
of the case. 
Pellet projectiles are useful for shooting moving targets, such as flying 
birds, or for skeetshooting since the pellets fired from the shotgun 
spread out when flying toward the target. So long as the target is in the 
range of the spread of the pellets, the pellets can hit the target. 
Shotshells available on the market, however, have a small angle of spread 
and are not suitable for short-distance shooting. 
Slug projectiles, which can be loaded in shotguns in place of pellet 
projectiles, are useful for shooting larger animals or immovable targets. 
The hit probability of the slug depends on the stability of the travelling 
attitude of the slug after being fired from the muzzle. In order to ensure 
the stability of the slug, it is known to fire the slug while rotating the 
same about its axis. The rotation of the slug contributes to increased 
stability due to the so-called gyro-effect. However, since shotguns do not 
have rifling in the barrel, unlike rifle, it is impossible to rotate the 
slug at a high speed. As a result, the hit probability of the slug is 
considerably smaller than that with a rifle. 
SUMMARY OF THE INVENTION 
The primary object of the present invention is to provide a wad which 
rotates at a high speed due to part of the energy of the explosion of a 
propellant, such as powder, to increase the spread of the pellets and to 
provide a high hit probability of a slug. Namely, the present invention 
provides a wad which can be used not only for pellets but also for a slug. 
According to the present invention, there is provided a wad for a shotgun 
shotshell having a case which has therein a propellant and a projectile 
held in the case by a crimp provided on the case. The wad is located in 
the case between the propellant and the projectile and has a substantially 
cylindrical seal member, usually called over powder wad, located adjacent 
to the propellant for enclosing the propellant in the case and a 
substantially cylindrical rotor body opposed to the seal member. The seal 
member and the rotor are connected to each other for relative sliding 
contact and relative rotation and have opposed end faces perpendicular to 
the axis of the shotshell. The seal member has at least one hole for the 
passage of the explosion gas. The rotor is provided, on the end face 
opposed to the seal member, with a plurality of gas jet grooves which are 
spaced from the axis and which extend in predetermined directions to be 
connected to the outer periphery of the rotor and to the hole of the seal 
member by means of the grooves defining the gas passages. The rotor 
comprises at least one radial projection projecting outward from the rotor 
and means for transmitting the rotation of the rotor to the projectile. 
The present invention is applicable to both projectiles in the form of 
pellets and in the form of single slugs.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIGS. 1 and 2 show a pellet shotshell and slug shotshell, both 
incorporating a wad according to the present invention, respectively. In 
the figures, numeral 1 designates a case, 2 a brass base, 4 powder 
(propellant), 5 a seal member and 6 a rotor. The brass base 2 has an end 
face 3 which is provided with a primer (not shown). The seal member 5 and 
the rotor 6 constitute a wad of the present invention. 
In the pellet shotshell shown in FIG. 1, the rotor 6 has blades 7 integral 
therewith which extend in directions parallel to the axial direction of 
the case 1. Between the blades 7 and the case 1 and on the periphery of 
the blades 7 are filled pellets 8 which are enclosed and prevented from 
coming out of the case 1 by means of a disc 9 which is, in turn, held in 
the case by a crimp 10 on the front end of the case 1. 
In the slug shotshell shown in FIG. 2 a slug 11 is placed in the case 1 in 
place of the pellets 8 in FIG. 1. A rotor 6c' is substantially similar to 
the rotor 6 shown in FIG. 1, except that the rotor 6c' has a rotation 
transmitting means for transmitting the rotation to the slug 11, which 
transmitting means will be described in detail later. 
In a first embodiment of the present invention, shown in FIGS. 3 and 4, the 
seal member 5 is made of a flexible plastic material, such as 
polyethylene, and is substantially cylindrical. The seal member 5 is 
provided, on its one face opposing the powder 4, with a recess 12. The 
seal member 5 has an axially extending center hole 13 which extends 
through the seal member 5 to provide an inlet passage for the explosion 
gas. The seal member 5 also has a conical projection 14 on the peripheral 
end of the seal member 5 adjacent to the recess 12. The conical projection 
14 spreads outward, so that it comes into close contact with the inner 
periphery of the case 1 to prevent leakage of the explosion gas 
therethrough. Alternatively, it is also possible to omit the conical 
projection 14 and provide a seal member 5d which has a diameter 
substantially equal to the inner diameter of the case 1, as shown in FIG. 
19. 
The rotor 6 is substantially cylindrical and is preferably made of a 
plastic material having a small friction coefficient. The axial length of 
the rotor is not limited. The diameter of the rotor 6 is smaller than the 
inner diameter of the case 1, which is in turn substantially identical to 
the inner diameter of the barrel of the shotgun (not shown). 
As can be seen from FIGS. 5 to 7, the rotor 6 has an end face 15 which is 
opposed to an end face 21 of the seal member 5 far from the recess 12 and 
which has a gas flowing groove (connecting groove) 16 having restrictions 
16a for restricting the gas flow. The groove 16 extends across the center 
of the rotor 6. On the rear end face 15 are also formed a plurality of jet 
grooves 17 which are connected to the terminal ends of the gas flow groove 
16 and which extend in predetermined directions. The jet grooves 17 start 
at starting points 22 and terminate at the periphery of the rotor 6. That 
is, the jet grooves 17 are connected to the outer periphery of the rotor 
6. 
Further, the rotor 6 has a plurality of projections, or at least one 
annular projection or ridge, integral with the rotor. The projections 
(projection) come into contact with the inner periphery of the case 1 to 
provide a uniform gap 20 (FIG. 1) between the outer periphery of the rotor 
6 and the inner periphery of the case 1. In the embodiment illustrated in 
FIGS. 5 to 7, the three projections 18 are provided on the three blades 7. 
The number of the projection(s) 18 and the blades 7 is not limited to 
three. 
The wad having the seal member 5 shown in FIGS. 3 and 4, and the rotor 6 
shown in FIGS. 5 to 7 operates in combination as follows. The seal member 
5 and the rotor 6 are located in the case 1 so that the end face 21 of the 
seal member 5 and the end face 15 of the rotor 6 face to and come into 
contact with each other. When the powder 4 is exploded, the seal member 5, 
the rotor 6, the pellets 8, and the disc 9 are pushed forward together by 
the explosive pressure to release the crimp 10, enter the barrel (not 
shown), pass through the barrel at a rapidly increasing speed, and finally 
are fired from the muzzle (not shown) at a high speed. 
Since the end face 21 of the seal member 5 which is subjected to the 
explosive pressure comes into press contact with the end face 15 of the 
rotor 6, the gas flowing groove 16 and the jet grooves 17 on the rotor 6 
are covered by the end face 21 of the seal member 5, so that a gas passage 
having a closed loop section is formed between the rotor 6 and the seal 
member 5 independently of the relative angular position, i.e., the 
relative angular phase of the opposed two end faces of the rotor 6 and the 
seal member 5. Since the gas flowing groove 16 is connected to the hole 13 
of the seal member 5, the explosion gas entering the hole 13 enters the 
gas flowing groove 16 and the jet grooves 17 and then is ejected from the 
outer periphery of the rotor 6 into the gap 20 which has a uniform width 
surrounding the periphery of the rotor 6 and the seal member 5; this 
uniform width can be ensured by the three projections 18 (FIGS. 1, 5, 6 
and 8). A reaction force of the adiabatic expansion due to the gas jet 
acts on starting points 22 of the jet grooves 17, so that causing torques 
due to the prepellant forces t.sub.1 and t.sub.2 (FIG. 6), which are 
indentical in magnitude to each other and are opposite in direction to one 
another, resulting in the rotation of the rotor 6. Thus, the rotor 6 
passes through the barrel while rotating. 
The explosion gas ejected into the gap 20 flows through a front end face 19 
(FIG. 5) of the rotor 6 opposed to the rear end face 15 into spaces 
between the pellets 8, so that the reduced high-pressure explosion gas 
blows off the light weight disc 9 and then is discharged from the muzzle. 
Note: Since the explosive gas ejected into the gap 20 is subject to an 
adiabatic expansion to be cooled therein, the gas passing through the 
spaces between the pellets 8 has a relatively low temperature, thus 
preventing the pellets from any accidental and undersirable adhesion or 
attachment to each other caused by heat. 
By the rotation of the rotor 6 and, accordingly, by the rotation of the 
blades 7 integral with the rotor 6, the charged pellets 8 enter the barrel 
while rotating about the axis of the barrel at an increased speed. The 
pellets are then fired from the muzzle while spreading outward in the 
tangential directions of the rotational movement due to the inertia of the 
rotational movement. 
In a second embodiment of the wad according to the present invention, an 
annular groove 23 and connecting grooves 24 for connecting the annular 
groove 23 and the hole 13 are provided on the end face 21 of the seal 
member 5a, as shown in FIG. 8. For combination with this seal member 5a 
shown in FIG. 8, the rotor 6a has gas introduction grooves (connecting 
grooves) 25 and a plurality of jet grooves 17a connected to the 
corresponding introduction grooves 25 on the end face 15, as shown in FIG. 
10. The connecting grooves 24 may be curved or straight and extend from 
the hole 13 in predetermined directions, so that the outer ends of the 
connecting grooves are connected to the annular groove 23. The 
introduction grooves 25 serve as restriction passages for restricting the 
gas flow therethrough. The introduction grooves 25 have starting points 
located on an imaginary circle corresponding to the inner diameter of the 
annular groove 23. The terminal ends of the introduction grooves 25 are 
connected, as mentioned before, to the corresponding jet grooves 17a which 
are in turn connected to the outer periphery of the rotor 6a. 
The wad according to the second embodiment operates as follows. When the 
powder 4 is exploded, the end face 21 of the seal member 5a comes into 
press contact with the end face 15 of the rotor 6a, so that gas passages 
are provided between the two end faces, similar to the first mentioned 
embodiment. Consequently, the high pressure explosion gas entering the 
hole 13 of the seal member 5a enters the connecting grooves 24 and then 
the annular groove 23 from the predetermined directions of the connecting 
grooves 24. As a result, the explosion gas circularly flows at a high 
speed in the annular groove 23 in the directions designated by the arrows 
in FIG. 8. The circulation of the explosion gas in the annular groove 23 
occurs in the clockwise direction when viewed from the side of the powder 
4. Therefore, the circulated gas enters the introduction grooves 
(connecting grooves) 25 at a high speed, since the annular groove 23 is 
connected to the introduction grooves 25 of the rotor 6a. The gas entering 
the introduction grooves 25 suddenly changes in direction of flow at the 
starting points 22a at which the jet grooves 17a are connected to the 
introduction grooves. The gas then comes into the jet grooves 17a and is 
ejected therefrom into the gap 20 (FIG. 1). The reaction force of 
adiabatic expansion due to the jet of the gas and the impacting force 
produced when the gas flow changes in direction as mentioned above at the 
starting points 22a both act on the rotor 6a in the same direction. 
Namely, the reaction force and the impacting force provide the propellant 
forces T.sub.1 and T.sub.2 (FIG. 10). It will be easily understood that 
the propellant forces T.sub.1 and T.sub.2 in the second embodiment are 
larger than the propellant forces t.sub.1 and t.sub.2 in the first 
embodiment. That is, a larger torque can be obtained in the second 
embodiment. Due to the large torque, the rotor 6a rotates in the clockwise 
direction when viewed from the side of the power 4, at higher speed. 
It should be noted here that the reaction force by the gas flow in the 
connecting grooves 24 gives a counter torque on the seal member 5a in the 
direction opposite to the direction of the circulation of the gas flow. 
Therefore, the seal member tends to idle in the opposite direction due to 
the counter torque. Therefore, in order to eliminate the possibility of 
the idling of the seal member 5a, it is possible to increase the depth of 
the recess 12 (FIG. 3) which is provided on the rear end face opposite to 
the end face 21 in which the connecting grooves 24, etc., are formed, so 
that the outer periphery of the barrel over a larger surface area when the 
seal member 5a expands outward due to the explosion gas pressure. The 
larger surface contact area of the outer periphery of the seal member with 
the inner periphery of the barrel increases the resistance against the 
rotation of the seal member. 
The explosion gas prevailing in the grooves (23, 24, 27 . . . etc.) 
provided on the end faces 15 and 21 of the rotor and the seal member has 
an extremely high pressure. Accordingly, an extremely small amount of high 
pressure gas enters between the end faces 21 and 15 of the seal member 5a 
and the rotor 6a, respectively, although the end faces are in close and 
press contact with each other, as mentioned above. The gas entering 
between the end faces 21 and 15 tends to separate the rotor 6a from the 
seal member 5a, so that the slide friction resistance between the end 
faces can be decreased, which otherwise prevents the rotation of the rotor 
6a. 
FIG. 9 shows a variant of the seal member shown in FIG. 8. In FIG. 9, the 
seal member 5b has a plurality of gas inlet holes 13a which extend 
parallel to the axis of the seal member and which are connected to the 
corresponding connecting grooves 24. The illustrated embodiment shows two 
gas inlet holes 13a, but more than two holes can be provided. Also, more 
than two connecting grooves 24 can be provided. The seal member 5b can be 
used in combination with the rotor 6a shown in FIG. 10. The operation of 
the wad having the seal member 5b and the rotor 6a is the same as that of 
the second embodiment mentioned above. Accordingly, no explanation 
therefor is given herein. 
In a third embodiment, the wad has a seal member 5c shown in FIGS. 11 and 
12 and a rotor 6c' shown in FIGS. 13 to 15. The seal member 5c shown in 
FIGS. 11 and 12 is provided, on the front end face 21, with an annular gas 
guide hole 26 which is coaxial to the axis of the seal member 5c and which 
has a diameter larger than that of the central hole 13a, and with 
connecting grooves 24a which extend in predetermined directions and which 
are bifurcated from the gas guide hole 26, similar to the connecting 
grooves 24 shown in FIG. 8. On the other hand, the rotor 6c' shown in 
FIGS. 13 to 15 has, on the rear end face 15, an annular groove 27 coaxial 
to the axis of the rotor and has introduction grooves (connecting grooves) 
25 identical to the introduction grooves 25 in FIG. 10. The annular groove 
27 is connected to the introduction grooves 25. The connecting grooves 24a 
of the seal member 5c are positioned so that the terminal ends of the 
connecting grooves 24a are located on an imaginary circle corresponding to 
the outer diameter of the annular grooves 27 of the rotor 6c'. On the 
outer periphery of the rotor 6c' adjacent to the front end face 19 are 
provided a plurality of projections 18a which have the same function as 
that of the projections 18 shown in FIG. 5. 
The slug 11 which is to be combined with the rotor 6c' has a circular 
cylindrical body with a semispherical head, as shown in FIGS. 16 and 17. 
The diameter of the cylindrical body of the slug 11 is smaller than the 
inner diameter of the case 1 and of a choke portion of the barrel (not 
shown), so that a gap 40 is provided between the slug 11 and the case 1, 
as can be seen from FIG. 2. The slug 11 is provided, on its cylindrical 
body, with a center cavity 28. On the rear end face of the slug 11 apart 
from the semispherical head are provided projections 29 and 30 which are 
located on an imaginary same circle and which are diametrically arranged. 
The projections 29 and 30 have inclined upper surfaces 31A and 31B which 
are tapered in such a way that the height of the projections 29 and 30 
gradually decreases in the direction of the rotational movement of the 
slug 11, as designated by the arrow in FIG. 18. 
On the other hand, as can be seen from FIG. 15, corresponding recessed 
grooves 32 and 33 are provided on the end face 19 of the rotor 6c' and on 
a same imaginary circle, so that the projections 29 and 30 can engage in 
the corresponding recessed grooves 32 and 33 in the direction of the 
rotational movement of the slug 11. Furthermore, the rotor 6c' has a 
central rod 34 on the end face 15. The rod 34 can be inserted in the 
central hole 13a of the seal member 5c. The rod 34 has a cross-section 
smaller than that of the hole 13a, so that a gap serving as a gas passage 
can be provided between the rod 34 and the inner wall of the hole 13a when 
the end face 21 of the seal member 5c is brought into press contact with 
the end face 15 of the rotor 6c'. In the illustrated embodiment, the rod 
34 has a regular square cross-section which is inscribed with a circle 
crosssection of the hole 13a. 
The rod 34 has a conical frustum-shape stop 35 on its front end. The 
smallest diameter of the top of the frustum is larger than the diameter of 
the gas guide hole 26 of the seal member 5c, so that the end face 15 of 
the rotor 6c' is spaced from the end face 21 of the seal member 5c at a 
distance S (FIG. 2) when they are combined in the case 1. 
FIG. 19 shows a variant of the third embodiment. In FIG. 19, the seal 
member 5d has an outer diameter substantially equal to the inner diameter 
of the case 1, so that the conical projection 14 as shown in FIG. 11 is 
dispensed with. The seal member 5d has a stop 37 located at the opening of 
the hole 13a adjacent to the powder 4 (FIGS. 2 and 19). The stop 37 is, 
for example, in the form of an easily breakable member, such as a film, 
layer, or band, having a thickness sufficient to hold a rod 34a of a rotor 
6d'. The stop 37 may either entirely or partly close the hole 13. In the 
embodiment shown in FIG. 19, the stop 37 is in the form of an annular 
breakable film having a small center hole 41. Also, the member 37 can be 
easily molded together with the sealing member 5d. On the other hand, the 
rod 34a provided on the center of the end face 15 of the rotor 6d' has no 
stop 35, unlike the third embodiment shown in FIG. 13. The rod 34a comes 
into contact with the stop 37 of the seal member 5d, so that the distance 
S is given between the end face 21 of the seal member 5d and the end face 
15 of the rotor 6d', as shown in FIG. 19. 
Preferably, a reinforcement disc plate 36 made of, for example, metal with 
a high rigidity is embedded in the rotor 6c' or 6d' to prevent the rotor 
from deforming due to the explosive pressure. 
The third embodiment and the variant thereof operates as follows. 
Immediately after the explosion of the powder 4, the seal member 5c or 5d 
acts to cause the slug 11 to move forward and come out of the case 1 by 
means of the front end face 19 of the rotor 6c' or 6d' through the rod 34 
or 34a. The slug 11, however, is held by the disc 9, which is in turn held 
by the crimp 10. Accordingly, the rotor 6c' or 6d' cannot move forward 
against the crimp 10, so that the explosion pressure increases. By the 
increased explosion pressure in case of the embodiment shown in FIGS. 11 
to 15, the hole 13a of the flexible seal member 5c expands. The stop 35 of 
the rod 34 thrusts through the hole 13a, resulting thus in press contact 
betweent the end face 21 of the seal member 5c and the end face 15 of the 
rotor 6c'. On the other hand, in case of the embodiment shown in FIG. 19, 
the stop 37 of the seal member 5d is broken, so that the two end faces 21 
and 15 come into press contact with each other, similarly to the 
foregoing. 
The displacement of the seal member 5c or 5d by the distance S (FIG. 2) 
during the initial stage of the explosion causes the expansion of the 
volume of the powder chamber in the case 1, so that the sudden increase of 
the explosion pressure is damped, resulting in a decrease of the peak 
value of the exposion pressure. This contributes to safe operation and 
also to a decreased recoil to the shoulder of the shooter. 
After that, the explosion pressure increases, so that the crimp 10 is 
released. Consequently, the explosion gas which has entered the gap around 
the rod 34 or 34a and in the hole 13a passes through the gas guide hole 26 
and the connecting grooves 24a, then comes in the annular groove 27 of the 
rotor 6c' or 6d' where the gas becomes a circulation flow in the 
directions designated by the arrow. When the gas flow comes into the 
introduction grooves 25, the gas flow changes in direction and then is 
ejected from the jet grooves 17a into the gap 20 (FIG. 2). The ejected 
gas, i.e., the exhaust gas, is discharged from the gap 40 into the barrel. 
Thus, the rotor 6c' or 6d' moves in the barrel while rotating at a high 
speed, similar to the second embodiment. 
The rotation of the rotor 6c' or 6d' is transmitted to the slug 11 by means 
of the projections 29 and 30, so that the slug 11 can be fired from the 
muzzle while rotating at a high speed. It should be noted that since the 
slug 11 is made of metal, it is harder than the rotor 6c' or 6d', which is 
made of plastic. Furthermore, the rotor is brought into press contact with 
the slug 11 due to the explosion pressure. Therefore, the recessed grooves 
32 and 33 can be dispensed with. Namely, even if the recessed grooves 32 
and 33 are not provided on rotor 6c' or 6d', the rotation of the rotor can 
be surely transmitted to the slug 11, since the projections 29 and 30 of 
the slug 11 press into the end face 19 of the rotor 6c' or 6d'. However, 
in the case where the projections are dispensed with, centering means for 
ensuring coaxial aligmnent of the slug 11 with the associated rotor is 
necessary. Such centering means can be, for example, a tubular flange 38 
provided on the rotor 6e', as shown in FIG. 21. The tubular flange 38 has 
a conical frustum-shaped bore 38a in which the peripheral rear or bottom 
end of the slug 11 is inscribed, so that the slug 11 is continuously held 
in the bore of the tubular flange of the rotor in coaxial aligmnent with 
the rotor. 
As is well known, the shotgun may have a choke portion near the muzzle. For 
this kind of shotgun, when the rotor 6c' or 6d' passes through the barrel, 
the projections 18a are subject to frictional resistance at the choke 
portion, thus resulting in a decrease of the propellant speed and the 
rotational speed of the slug. Since the projections 29 and 30 have the 
tapered upper surfaces 31A and 31B (FIG. 18), however, the slug 11 
separates from the associated rotor at the moment of reduction of the 
propellant speed and the rotational speed of the slug 11. Namely, the 
inclined projections 29 and 30 construct a one-way clutch. Accordingly, 
the separation of the slug from the associated rotor enables the slug 11 
to pass through the barrel without coming into contact with the choke 
portion. Namely, a slug shotshell having a wad in which the slug is 
connected to the associated rotor by means of inclined projections which 
serve as one-way clutch, according to the present invention enables a high 
hit probability without adverse effects of the choke portion of the gun 
barrel. 
As can be understood from the above discussion, in the above-mentioned 
embodiments, the blades 7 are transmitting means for transmitting the 
rotation to the projectile in the form of pellets, and the projections 29 
and 30 and the recessed grooves 32 and 33 are similar transmitting means 
for the projectile in the form of a slug. That is, the present invention 
can be advantageously applied to a pellet shotshell as well as to a slug 
shotshell. 
Another application of the present invention is shown in FIGS. 20 and 21. 
In FIGS. 20 and 21, the rotor 6e' has the tubular flange 38 which has a 
conical frustum-shaped bore 38a opening to the front end 19, as mentioned 
before. The flange 38 has on its periphery a plurality of elogated 
projections 39 extending parallel to the axis of the rotor 6e'. On the 
bottom surface 19a of the bore 38a are provided projections 29a and 30a 
which have inclined upper surfaces similar to the projections 29 and 30 
and which are located on a same imaginary circle. The projections 29a and 
30a are also diametrically arranged, similar to the projections 29 and 30. 
A slug 11a to be connected to the rotor 6e' is similar to the slug 11, 
except that recessed grooves 32a and 33a are provided on the slug in place 
of the projections 29 and 30. The projections 29a and 30a are engaged in 
the corresponding recessed grooves 32a and 33a. In this embodiment, the 
elongated projections 39 may be inclined with respect to the axis of the 
rotor 6e', as shown at 39' in FIG. 20. Since the rotor 6e' is fired from 
the muzzle while keeping inscribing contact of the projections 39 with the 
inner periphery of the barrel, the slug 11a is also fired from the muzzle 
while in axial alignment with the axis of the barrel, thus resulting in a 
high hit probability. The rotor 6e' is preferably used in combination, 
with the seal member 5 shown in the first embodiment, wherein the 
transmission of the rotation and the operation one-way clutch due to the 
inclined projections 29a and 30a are the same as those of the foregoing. 
When the inner diameter of the bottom surface 19a (FIG. 21) is 
substantially identical to the outer diameter of the slug 11a, the 
projection 30a of the rotor 6e' and the recessed groove 33a of the slug 
11a both can be dispensed with, allowing the provision of only one 
projection on the rotor 6e' for transmitting the rotation of the rotor to 
the slug 11a, since the slug 11a can be snugly inserted in the inner 
diameter of the rotor 6e', without the need for the help of the projection 
30a. 
FIG. 22 shows a fourth embodiment of the present invention, which is a 
modification of FIGS. 9, and 11 to 15. As can be seen from FIG. 22, the 
seal member 5e has four holes 13b in place of the hole 13a (FIG. 9) and 
the gas guide hole 26 of the seal member 5c shown in FIGS. 11 and 12. The 
holes 13b extend from the bottom of the recess 12 to the end face 21. To 
the respective holes 13b are connected connecting grooves 24b which extend 
in the predetermined directions from the respective holes 13b. The rotor 
6f' which is to be combined with the seal member 5e shown in FIG. 22 is 
illustrated in FIG. 23. The rotor 6f' is for the slug. The rod 34 as shown 
in FIG. 13 is dispensed with in the rotor 6f' shown in FIG. 23. Also, the 
annular grooves 27 of the rotor 6f' are composed of four discontinuous 
groove elements 27a, 27b, 27c and 27d which are separated from each other 
by partition walls 42. The introduction grooves 25 having the jet grooves 
17a connected therto are connected to the respective separate annular 
groove elements 27a, 27b, 27c, and 27d. For other constructions, the rotor 
6f' is similar to the rotor 6c' shown in FIGS. 13 to 15. In the fourth 
embodiment, the operation of the wad is similar to that of the wad of the 
above-mentioned third embodiment except that the explosion gas is 
introduced by the independent four holes 13a and that the seal member 5e 
and the rotor 6f' come into face contact with each other by means of the 
end faces when they are located in the case 1, since no rod 34 is 
provided, as mentioned before, thus resulting in no expansion of the 
powder chamber at the initial stage of the explosion. 
The connecting grooves 24b of the seal member 5e are shaped and sized so 
that the front ends 24b' of the connecting grooves 24 bridge the adjacent 
two annular groove elements 27a, etc., when the front ends are located on 
the respective partition walls 42 of the rotor 6f'. Accordingly, the gas 
passages are not discontinued by the partition walls 42. 
The fifth embodiment shown in FIGS. 24 to 28 is a wad having a seal member 
5f, which is a modification of the seal member 5d shown in FIG. 19, and a 
rotor 6g, which is a modification of the rotor 6 shown in FIGS. 5 to 7. 
As can be seen in FIGS. 24 to 26, the seal member 5f has, on the end face 
21 thereof, a tubular extension 43 which has an outer diameter 
substantially equal to the inner diameter of the case 1. The tubular 
extension 43 extends in the axial direction of the seal member and is 
integral with the latter. The tubular extension 43 has, for example, four 
axially extending slits 44. Furthermore, in place of the stop 37 shown in 
FIG. 19, a stop 37a in the form of a cross-shaped band is provided on and 
molded integral with the seal member 5f. On the other hand, the rotor 6g 
shown in FIGS. 27 and 28 is similar to the rotor 6 shown in FIGS. 5 to 7 
except that an axial center rod 34a' identical to the rod 34a provided on 
the rotor 6d' shown in FIG. 19 is provided on the end face 15. The 
provision of the rod 34a' causes the gas flowing passage on the end face 
15 to be divided into two passages 16'. As mentioned before, the rod 34a' 
(identical to the rod 34a) has a cross-section smaller than that of the 
hole 13b of the seal member 5f, and accordingly, a gap is provided between 
the rod 34a' and the hole 13b for allowing the flow of the explosion gas 
therethrough. The explosion gas then enters the two gas flowing passages 
16' and comes into the respective jet grooves. 
The rotor 6g is received in the tubular extension 43 of the seal member 5f 
in such a way that the end face 15 of the rotor 6g is opposed to the end 
face 21 of the seal member 5f. Therefore, the distance S is provided 
between the two end faces by the engagement of the rod 34a' and the stop 
37a, similarly to the third embodiment, as shown in FIG. 2. The 
projections 18b of the rotor 6g are such that the projections 18 come into 
snug contact with the inner surface 45 of the tubular extension 43. Also, 
since the diameter of the outer periphery 46 of the rotor 6g is smaller 
than the diameter of the inner surface 45 of the tubular extension 43, a 
uniform annular gap similar to the gap 20 as shown in FIGS. 1 and 2 is 
provided therebetween. 
The operation of the fifth embodiment is similar to that of the embodiment 
shown in FIG. 19 except for the following points. 
1. In comparison with FIG. 19, which shows the wad for a slug shotshell, 
the wad of the fifth embodiment is for a pellet shotshel. Accordingly, the 
blades 7 serve as a transmitter of the rotational movement of the rotor 
6g. 
2. The cross-shaped band-like stop 37a which is provided in place of the 
annular film 37 in FIG. 19 is broken by the front end of the rod 34a' at 
the explosion of the powder. 
3. The explosion gas ejected from the jet grooves 17 enters the spaces 
between the pellets 8 charged between the tubular extension 43 and the 
blades 7 through the annular gap around the outer periphery 46 of the 
rotor 6g and then is discharged in the barrel. 
4. The tubular extension 43 serves as a container of the pellets 8 which 
contributes to the prevention of the pellets 8 from deforming due to the 
contact of the pellets with the barrel during the passage of the seal 
member 5f in the barrel and also to the prevention of the lead, of which 
the pellets are made, from being stuck to the inner surface of the barrel. 
It should be noted that the number of the jet grooves 17 and the passages 
16' in FIGS. 27 and 28 is not limited to two but may be more than two. 
It should also be noted that the discontinuous annular groove elements 27a 
etc. decrease the leakage of the explosion gas therethrough, in comparison 
with the continuous annular groove 27 during the circulation of the gas 
therein. 
FIGS. 29 to 31 show a sixth embodiment of the wad according to the present 
invention, which embodiment is a modification of the first embodiment 
mentioned above. 
The seal member 5g shown in FIG. 29 has no stop 37 (FIG. 19) and no annular 
gas guide hole 26 (FIG. 19). Instead, the seal member 5g has a hole 13c 
which is deeper than the hole 13a of the seal member 5d. In FIG. 29, the 
longer depth of the hole 13c is designated at "d". 
On the other hand, the rotor 6h shown in FIGS. 30 and 31 has one blade 7a 
which has no projection on its periphery, and a central rod 34b with 
elongated channels 47 which extend in parallel to the axis of the rotor. 
The channels 47 are connected, at the ends thereof adjacent to the end 
face 15 of the rotor 6h, to the gas jet grooves 17 by means of the 
connecting grooves 16'. 
As can be seen from FIG. 30, the central rod 34b of the rotor 6h is snugly 
fitted in the hole 13c of the seal member 5g for rotation. In the sixth 
embodiment, since the seal member 5g has a larger wall thickness in the 
axial direction, in comparison with, for example, FIG. 19, to allow the 
provision of the longer hole 13c of the length "d" (FIG. 29), the rotor 6h 
can be firmly held by the seal member 5g when the central rod 34b is 
inserted in the hole 13c of the seal member 5g, so that the rotor 6h can 
be put in the crimped case 1 coaxially to the latter to provide the 
uniform gap 20 around the periphery of the rotor 6h without the provision 
of the projections on the periphery of the rotor. 
In the sixth embodiment, the explosion gas first enters the channels 47 and 
passes through the connecting grooves 16' and is then discharged from the 
gas jet grooves 17. The function of the sixth embodiment is the same as 
that of the first embodiment. 
As can be seen from the above, according to the present invention, in case 
of a pellet shotshell, the pellets are fired from the muzzle after a fully 
high rotational speed is given to the pellets. Accordingly, the pellets 
are forced to spread to a wide range even if a choked barrel shotgun is 
used. It has been experimentally confirmed that a uniformly distributed 
wide pattern of the pellets is obtained according to the present 
invention. Further, in case of a slug shotshell, since the slug can be 
rotated at a high speed, the hit probability of the slug can be increased.