Ammunition and explosives – Projectiles – Composite
Reexamination Certificate
2000-12-26
2003-01-07
Tudor, Harold J. (Department: 3641)
Ammunition and explosives
Projectiles
Composite
C102S439000, C102S448000, C102S522000, C244S003230
Reexamination Certificate
active
06502516
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a projectile in the form of a sabot shotgun slug assembly and, more particularly, to a sabot which supports a slug in non-rotative engagement therewith and which remains together downrange until target impact.
BACKGROUND OF THE INVENTION
A sabot for use in positioning a bullet or projectile in a gun barrel is well known. Essentially, a sabot is a plastic sleeve that holds the projectile during firing. A typical prior art sabot includes a cylindrical body having a receiving chamber accessible at one end and a base at the other end.
It is known to use a sabot for positioning the bullet within the barrel of a rifle, muzzleloader or shotgun. Sabots may be used with both conical-shaped bullets as well as traditional lead ball bullets. When used with a firearm with a rifled barrel, the sabot is used to impart rotation to the projectile as it travels down the gun barrel after firing. In particular, the sabot is typically formed to have a diameter the same as the grooved diameter of the rifled barrel so that the sabot is pressed into the rifling after firing. As is well known, the principal behind rifling in a gun barrel is to produce a spin on the projectile about its longitudinal axis as the projectile travels through the gun barrel. The spin produces a gyroscopic effect on the projectile giving the projectile greater stability and accuracy. Sabots are also used in smoothbore gun barrels for increasing the stability of the projectile during firing.
In general, sabots are formed in two-piece sections or as multi-fingered sections that are configured to surround the exterior of the projectile. A typical two-piece sabot is disclosed in U.S. Pat. No. 5,479,801 to Kinchin. In this reference, a two-piece sabot surrounds a slug that is non-rotating and connected to the slug so that the rotary motion, which is imparted to the sabot by contact between its external surface and the rifling in a gun barrel, is transferred directly to the slug. Upon exiting the gun barrel, the two-piece sabot splits apart and falls away from the slug. Hence, the sabot does not accompany the slug downrange as it approaches its target.
As stated, sabots also are provided in a multi-fingered configuration. A typical prior art multi-fingered sabot is disclosed by U.S. Pat. No. 5,415,102 to White et al. The sabot disclosed therein has a plurality of petals or leaves that are configured to extend over a bullet. Upon discharge from a gun barrel, the petals or leaves open up to release the bullet to travel downrange toward its target.
The difficulty with two-piece and multi-fingered sabots is that they tend to open up unevenly when under pressure in the gun barrel and upon exit from the gun barrel. This causes the bullet or projectile to become out of line with the central axis of the gun barrel, thus making the projectile inaccurate.
The problem with a one piece collet cup sabot is that when it is under pressure the pressure will only expand the top of the cup which is open, the base, being solid, cannot expand fully into the rifling or the bore. The one piece tube type sabot, which is open at both ends will expand uniformly and will engage the rifling or the bore of the barrel along its full length.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a projectile in the form of a sabot shotgun slug that has increased accuracy.
A sabot shotgun slug assembly includes a hollow cylindrical sabot, a pressure wad positioned at one end of the sabot for facilitating firing. A deformably expandable slug is insertably accommodated in the cylindrical sabot at the other end thereof. The cylindrical sabot includes a plurality of longitudinally extending grooves formed along an internal cylindrical wall thereof. Upon firing of the slug assembly, the slug deformably expands to fill the grooves in the sabot to maintain non-rotative engagement between the slug and the sabot.
As more particularly described by way of preferred embodiments, the sabot shotgun slug assembly includes a cylindrical slug, a cylindrical sabot positioned about the slug and a pressure wad that co-acts with the slug and the sabot. The central slug defines a central bore that extends partially therethrough. The slug is preferably formed of a deformable metal. The sabot defines a plurality of longitudinally extending internal grooves. The pressure wad has two ends, with a gas seal at a first end thereof and a post at a second end thereof. In addition, the pressure wad includes shock-absorbing members formed between the gas seal and the post. The post is positioned within the central bore defined by the slug. In operation, after the sabot shotgun slug assembly is fired, the slug deforms axially and expands outward to fill the plurality of grooves defined in the sabot which mechanically locks the slug and sabot together to stop any slipping movement of the slug when torque is transferred to the slug through the sabot due to the twist of the rifling. The slug simultaneously expands inward to engage the post such that the slug, the sabot and the pressure wad remain connected together while travelling downrange toward a target.
The sabot and the gas seal preferably have substantially the same outer diameter. The pressure wad may further include an intermediate disk formed integrally with the shot absorbing members. The intermediate disk and the gas seal may have substantially the same outer diameter as the sabot. The shock absorbing members are preferably formed as chevrons extending between the gas seal and the post.
In an alternative embodiment, the sabot shotgun slug assembly includes a cylindrical slug, a cylindrical sabot positioned about the slug, a pressure wad and a separate insert support member. The cylindrical slug defines a central bore extending partially therethrough. The slug is preferably formed of a deformable metal. The sabot defines a plurality of longitudinally extending internal grooves. The pressure wad has a gas seal and a plurality of shock absorbing members. The insert support member includes a post portion and a disk portion. The post portion is positioned within the central bore defined by the slug. In operation, after the sabot shotgun slug assembly is fired, the slug deforms axially and expands outward to fill the plurality of grooves defined in the sabot. This action mechanically locks the slug and sabot together to stop any slipping movement of the slug when torque is transferred to the slug through the sabot due to the twist of the rifling. Simultaneously the slug expands inward to engage the post portion such that the slug, the sabot, the insert support member remain connected together while travelling downrange toward a target. The pressure wad falls away when exiting the barrel.
A complete understanding of the present invention will become apparent from the following detailed description, in conjunction with the drawings, wherein like parts are designated with primed reference numerals.
REFERENCES:
patent: 4043267 (1977-08-01), Hayashi
patent: 4471699 (1984-09-01), Turco et al.
patent: 4587905 (1986-05-01), Maki
patent: 5086703 (1992-02-01), Klein
patent: 5415102 (1995-05-01), White et al.
patent: 5479801 (1996-01-01), Keller
patent: 5479861 (1996-01-01), Kinchin
patent: 6067909 (2000-05-01), Knoster, Jr.
patent: 6105506 (2000-08-01), Gangale
patent: 6186071 (2001-02-01), Fry
patent: 2903286 (1980-08-01), None
Hoffman & Baron LLP
Tudor Harold J.
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