Case hone

Abstract

A tube with a conical mouth slides over the neck of an ammunition cartridge and is pressed against the shoulder to align the case. A neck reamer translates and rotates within the tube, the tip being inserted into the neck. Both mouth and tip are replaceable, come in different sizes, and come with smooth or abrading surfaces. The tip and the mouth are coaxial. The mouth perfects the shoulder surface and the tip perfects the neck interior. This results in a cartridge case having a neck with an interior wall that is a perfect cylinder that is coaxial with the perfected exterior of the conical shoulder.

Claims

1. An apparatus for honing an ammunition cartridge case, said case comprising a conical shoulder and a cylindrical neck, said apparatus comprising: a shoulder-hone comprising a bore, said bore terminating with a conical mouth, an axis of said mouth being co-axial with an axis of said bore, said mouth having a cone angle and median diameter substantially equal to the cone angle and median diameter of said shoulder of said case, said mouth of said shoulder-hone being pressed against said shoulder of said case during operation of said apparatus; the surface of said mouth of said shoulder-hone being either smooth, cutting, or abrading; said mouth of said shoulder-hone being incorporated into, fixedly attached, or removably attached to said shoulder-hone; neck-reamer comprising a shaft and a tip, said shaft translating and rotating within said bore of said shoulder-hone during operation of said apparatus, said tip comprising a cylindrical working surface, an axis of said working surface of said tip being co-axial with an axis of said shaft of said neck-reamer; said working surface of said tip of said neck-reamer being either smooth, cutting, or abrading; said tip of said neck-reamer being incorporated into, fixedly attached, or removably attached to said neck-reamer.

2. An apparatus according to claim 1 further comprising a means for trimming the end of said neck of said case, said means including one or more radially oriented cutting blades incorporated into said tip of said neck-reamer.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 illustrates, with an exploded view, the preferred embodiment of the case hone, which is a bench top mounted hand-operated device made of steel and brass, or similar materials. Critical dimensions will change to match the cartridge the hone is designed for.

(2) FIG. 2 illustrates, with an exploded view, alternative embodiments of various elements of the case hone.

(3) FIG. 3 is a detail view of the reamer tip illustrated in FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE INVENTION

(4) Disclosed is a novel design for a tool that prepares rimless shoulder breeching rifle cartridge cases for loading. The objective of this invention is improved concentricity of the bullet to the barrel bore in order to reduce in-flight wobble and thereby improve downrange accuracy. Similar tools are called trimmers but I call this tool a hone because it functions primarily by removing a very small amount of material from the shoulder exterior and the neck interior, producing thereby a smooth perfectly shaped shoulder exterior and neck interior.

(5) The tool is used in the following manner. 1) Secure the base of the frame (1b) to a table or bench top. 2) Insert a collet (4) sized for the case (5) into the mounting hole (2) in the head block (la) and secure it with the collet screw (3), but do not tighten. 3) Select the proper size and type of shoulder hone (7) for the case (5) and the operation to perform. The mouth (8) of the shoulder hone (7) is a conical surface, the cone angle and nominal diameter must match the conical shoulder (5a) of the cartridge case (5). The mouth (8) is available in two types: a hone, which has a mildly abrasive surface; and a pilot, which has a smooth surface. 4) Insert the case (5) into the collet (4). 5) Insert the shoulder hone (7) into the bushing (6) in the tail block (1c) until the mouth (8) is pressing against the shoulder (5a) of the case (5), which aligns the case, and tighten the collet screw (3). 6) If the mouth (8) is an abrasive type, rotate the shoulder hone (7) with the shoulder hone handle (9) while maintaining gentle pressure against the case, removing only enough material from the shoulder as is necessary to perfect the surface of the case shoulder (5a). Removing too much material will weaken the case (5), producing a potentially dangerous situation, so this operation will not always be performed. The primary purpose of the mouth (8) is to align the case (5) for the following operations so a smooth surfaced pilot type of mouth (8) can be used align the case (5) while avoiding removing material from the shoulder (5a) (this presumes the shoulder is already well formed). 7) Choose the appropriate size and type of reamer tip (11), which is a cylinder with an outer working surface. The diameter must match the interior of the case neck (5b). The types are: reamer, pilot, reamer and trimmer, pilot and trimmer. The reamer type has a mildly abrasive working surface ((11a) of FIG. 3) that removes material from the interior surface of the neck (5b). The pilot type has a smooth surface so that it does not remove material but only functions as an alignment feature. The reamer and trimmer type includes radially oriented cutters ((11b) of FIG. 3) that removes material from the interior and then also shaves the end of the neck (5b) to shorten it. The pilot and trimmer type has a tip with a smooth cylinder and radially oriented cutters (11b) that only shave the end of the neck (5b). 8) Attach the reamer tip (11) to the reamer shaft (10). Then insert the shaft (10) into the bore of the shoulder hone (7a) until contact is made with the neck (5b). 9) While ensuring that the mouth (8) remains pressed against the case shoulder (5a), maintaining alignment, rotate the reamer handle (13) while slowly pressing the reamer into the neck (5b). If the tip (11) is the reamer only type it is inserted until it stops on the end of the neck. If the tip includes a trimmer (11b) then it is inserted until the lock ring (12) is pressed against the rear of the shoulder hone. The lock ring (12) and handle (13) are threaded onto the reamer shaft (10) and adjusted to set the length the neck (5b) is trimmed to. 10) Retract the shoulder hone (7) and reamer shaft (10), loosen the collet screw (3), then remove the case (5) and inspect.

(6) The result of the above operations will be a case (5) with a shoulder (5a) having an exterior surface that has been machined to a perfect truncated cone and a neck (5b) having an interior surface that has been machined to a perfect cylinder that is coaxial with the shoulder (5a). When a cartridge is assembled from a case (5) thus prepared the axis of the bullet will be perfectly coaxial with the shoulder (5a). When that cartridge is of the shoulder breeching type it will therefore, when inserted into a rifle chamber, position the bullet perfectly coaxial with the bore of the barrel. Therefore, upon firing the bullet will rotate about its center of mass and, therefore, in-flight wobble will be greatly reduced.

(7) This result is achieved because of the unique arrangement of the elements of the design, but careful manufacturing is required to realize it. The collet (4) is coaxial with the bushing (6) in the tail block (1c). There is a slip fit between the shoulder hone (7) and the bushing (6). The conical mouth (8) is coaxial with the outer cylindrical surface of the shoulder hone (7) and has a cone angle and nominal diameter that matches the conical shoulder (5a) of the case (5). It is the compressive force between the two matching conical surfaces, the mouth (8) and the shoulder (5a), that aligns the case (5). Maintaining this compressive force is essential to maintaining alignment. The bore in the shoulder hone (7a) is also coaxial with the outer surface and the mouth (8). There is a slip fit between the reamer shaft (10) and the bore in the shoulder hone (7a). The cylindrical working surface of the reamer tip (11a) is coaxial with the cylindrical outer surface of the reamer shaft (10). Therefore, the working surface of the reamer tip (11a) will be coaxial with the case shoulder (5a) throughout the operation of the tool.

(8) FIG. 2 illustrates an alternative embodiment of the case hone. This embodiment does not work the shoulder of the case (5a). The alignment function of the mouth (8) has been moved to an alignment bushing (18) housed in a modified head stock (14a), which has a bore ending in a conical cup (18a) with a cone angle and nominal diameter that matches the case shoulder (5a). A thumb screw (19) retains the alignment bushing (18) in the head stock (14a). Two thumb nuts ((15a) and (15b)) turn on threaded shafts ((16a) and (16b)) to press a retaining cap (17) against the head of the case (5) to generate the compressive force between the shoulder (5a) and the conical cup (18a) necessary to achieve and maintain alignment of the case (5). A modified tail stock (14c) holds a modified bushing (20) with an inner diameter that matches the reamer shaft (10). The conical cup (18a) is coaxial with the tail stock bushing (20) which ensures that the reamer tip (11) is coaxial with the case shoulder (5a).

(9) FIG. 3 is an enlarged view of the reamer tip (11) illustrating the reamer working surface (11a) and trimmer (11a) option discussed above.