US3848350A

US3848350A - Dry fire cartridge or shot shell

Info

Publication number: US3848350A
Application number: US00387285A
Authority: US
Inventors: H Seminiano
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-08-10
Filing date: 1973-08-10
Publication date: 1974-11-19
Anticipated expiration: 1991-11-19

Abstract

A dummy center-fire cartridge or shotgun shell having a flexible shock-absorbing plastic ''''primer'''' or non-explosive body or slug, is disclosed for use in dry-firing a firearm without harm to or breaking of the fing pin or other parts of the gun. The plastic body is formed or molded within the primer pocket of an empty cartridge case and is formed around and into any indentations or holes such as the flash hole so that it is rigidly affixed therein. The plastic body is composed of a non-shrinking thermosetting resin such as polyurethane, characterized by toughness, high tensile strength; and tear, chemical and abrasianresistance. The plastic body allows partial travel of the firing pin therein with little or no rebound tendency. The impression made in the plastic body is quickly healed because of the elastic memory of the plastic so that repeated hammer falls on the same cartridge or shell are not detrimental to the firing pin or the plastic body.

Description

United States Patent [191 Seminiano Nov. 19, 1974 DRY FIRE CARTRllDGE 0R SHOT SHELL [76] Inventor: Herman .1. Seminiano, 3720 W. 61st St., Chicago, 111. 60629 [22] Filed: Aug. 10, 1973 [21] Appl. No.: 387,285

Primary Examiner-Benjamin A. Borchelt Assistant Examiner--C. T. Jordan Attorney, Agent, or Firml-larbaugh and Thomas [57 ABSTRACT A dummy center-fire cartridge or shotgun shell having a flexible shock-absorbing plastic primer or nonexplosive body or slug, is disclosed for use in dry-firing a firearm without harm to or breaking of the ting pin or other parts of the gun. The plastic body is formed or molded within the primer pocket of an empty cartridge case and is formed around and into any indentations or holes such as the flash hole so that it is rigidly affixed therein. The plastic body is composed of a non-shrinking thermo-setting resin such as polyurethane, characterized by toughness, high tensile strength; and tear, chemical and abrasian-resistance. The plastic body allows partial travel of the firing pin therein with little or no rebound tendency. The impression made in the plastic body is quickly healed because of the elastic memory of the plastic so that repeated hammer falls on the same cartridge or shell are not detrimental to the firing pin or the plastic body.

6 Claims, 7 Drawing Figures DRY FIRE CARTRIDGE OR SHOT SHELL BACKGROUND OF THE INVENTION A number of dry-fire cartridges are available employing a spring loaded pad in place of the primer. Some of these devices are quite expensive because a relatively strong spring must be used to withstand the hammer blow and means must be provided to hold and guide the spring as it absorbs the inertia of the firing pin. These means must insure proper return of the pad after each dry-firing and consequently are subject to malfunction due .to inclusions of dirt and failure to provide proper and instantaneous shock absorption and return of the pad when the firing pin is retracted. The shock absorbing parts must be specially machined from bar stock and particularily formed for each caliber or type of gun. Since the cases are also specially formed to accommodate the inner spring mechanism, the cost is increased and, in some instances, the end products will not chamber in all guns of the same caliber or gauge.

SUMMARY OF THE INVENTION In accordance with this invention the foregoing disadvantages are avoided by completely sealing and filling the primer pocket of a used or empty brass cartridge, the primer pocket of a used shotgun shell or the primer cup of a spent primer within the primer pocket of a spent shell with a tough resilient plastic composition. By these means an inexpensive, readily formed shock absorber for the firing pin is formed which can be used repeatedly in a firearm for dry-firing practice without harm to thefiring pin. Because spent or empty cases are used, no problems of chambering the dummy rounds are incurred. One particular advantage of the use of plastic for this purpose is that the shock of stopping the firing pin is distributed over the surface of the pin as it penetrates the plastic so that there is no wearing because of point contact with a pad. Also the forces are quickly absorbed within a short distance of travel of the pin. The further the pin travels into the plastic primer the more the resistive forces are multiplied.

The dummy cartridges or shells of this invention accommodate any shape of firing pin and the forces of the hammer blow are absorbed axially in a short travel distance or penetration into the plastic body. The depth of penetration may be less than the penetration of the pin into a real primer so that there is no battering of the breech block or cylinder. This assures that no damage will result from dry firing any type of guns. Another advantage with some guns is the absence of any perceptible sound since metal-to-metal contact is avoided and only the click of the scar and hammer spring are audible to the user. These and other advantages will become apparent or be set forth as the invention is described.

DESCRIPTION OF THE DRAWINGS Illustrative examples of the invention are shown in the drawings in which:

FIG. 1 is a perspective view of a revolver or pistol center-fire cartridge having a plastic primer" or body formed in accordance with this invention;

FIG. 2 is a cross-sectional view taken along the lines 2--2'of FIG. 1;

FIG. 3 is a cross-sectional view of a shotgun shell with the primer pocket containing a plastic body formed therein;

FIG. 4 is a cross-sectional view of a shotgun shell with the primer cup therein and the plastic body of this invention formed within the primer cup; and

FIGS. 5, 6 and 7 are cross-sectional views of the dummy primer of this invention being struck by the firing pin of a gun and retracted therefrom to show the substantially instantaneous recovery of the plastic from this kind of indentation.

DESCRIPTION OF TI-IE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, the cartridge 10 is shown having the brass case 12 with the flanged head 14 and the integral primer pocket 16. Although the case has been properly fitted with a bullet 18, the interior 20 is devoid of powder and the round is absolutely safe for dry firing. Any type of empty cartridge or shell case can be used and the rimmed case 12 is merely illustrative. In order that this round will not be confused with a live round of the same caliber, the hole 22 is drilled through the wall of the case 12 into the chamber 20. This is the earmark of a dummy round to the shooter. The cartridge can also be color-coded.

The primer pocket 16 has the flash hole 24 at the bottom or interior end which is for the purpose of allowing the primer flame or flash to reach the powder which ordinarily would occupy all or part of the space 20 so that the cartridge will fire. After the cartridge is fired the powder and bullet are gone and the primer is spent. Upon removal of the primer, the primer pocket I6 is normally readied for re-loading by cleaning and inserting a new primer followed by a measured charge of powder for the chamber 20 and the seating of a bullet 18 to the proper depth. Re-loading is a common ractice among sportsmen who desire to prepare their cartridges exactly to the shooting characteristics of their guns or in order to reduce the cost of shooting.

In accordance with this invention a spent cartridge case or a new unloaded case is transformed into a safe dry-firing practice or dummy round by filling the primer pocket 16 with the plastic body or primer" 26 in such a manner that the plastic flows into intimate contact with the cup filling all voids and is in intimate contact at the interface 28 with any roughness or scratches that may exist on the surface of the cup and also make certain that a portion of the plastic body flows into the flash hole 24 to form the excess blob 29 on the outside of the cup. Any excess plastic is removed, after setting, so that the outer surface 30 against which the firing pin strikes is flat and flush with the cartridge head 14. By so forming the plastic body 26 it does not dislodge during use nor interfere in any way with the operation of a firearm.

FIG. 3 shows a shotgun shell 32 having a cardboard jacket 34 and a brass head 35 crimped thereover. A primer pocket 36 is formed into the plastic base 38 by means of a number of tabs of the brass face bent into a conical recess. The base has the flash hole 40 which extends into the interior 42 of the case, and serves the same purpose as the flash hole 24 in the pistol cartridge. The tabs forming the primer pocket are spaced from each other so that the plastic body or primer 26 flows between and about their edges and also flows into the irregularities of the flash hole 40 as shown at 41 so that there is no possibility of dislodgement of the false primer during use. The balance of the interior 42 of the shell is filled with any desired number of wads 44 and the end crimped as at 46 to complete the dummy shotgun round. The presence of the wads and crimping gives the round the proper density or firmness and length so that it can be chambered like a regular round into the breech of a gun and also be handled by the ejector after dry-firing.

FIG. 4 illustrates a modern plastic shotgun shell 50 with a unitary casing 52 and base 54 all made of plastic and encased by the brass head 55 with a different type of primer pocket 56, still retaining the spent primer cup 58 from which the primer cap and anvil have been removed. The use of the primer cups retains the appearance of a regular round and provides a sharp edged flash hole 60 into which the plastic body 26 flows to lock therein by means of the excess blob 29. Suitable shaped wads 62 and regular wads 44 are used to fill the case 52 and the end is re-crimped at 46.

FIG. shows a dummy primer or plastic body 26 of this invention within a primer pocket 16, securely locked by the excess blob 29 protruding through the flash hole 24 as same is struck bya firing pin 64 guided by the breech block 66 of a gun. The firing pin 64 has a typical blunt end 68 which extends sufficiently through the bore 70 of the breech block 66 to strike and fire a primer under normal conditions. As shown the use of the plastic body 26 allows the pin 64 to penetrate about the extent of its normal travel while the force is absorbed. When the gun. is re-cocked and the pin being retracted as shown in FIG. 6, the indentation 72 in the plastic body 26 has already recovered by 90 percent and moments later substantially full recovery of the indentation has been accomplished as shown in FIG. 7. Even after extended and repeated use only a vestige of the indentation will remain as shown by the smaller indentation line 72' in FIG. 7, and the plastic body 26 retains its ability to safely cushion the penetration of the firing pin at any time. This is also true of more pointed firing pins and blunt or tapered or wedge Dl004-59T. Preferably, the shrinking during casting or molding will be about 0.0002 to 0.0004 in/in at about 75F. and the plastic should be resistant to oils, greases and cleaning solvents normally used with guns. Dyes can be'used in the compositions as an added coded index for the shooter to indicate a dummy round.

In accordance with one aspect of this invention, the proprietary product known under the trademark FLEXANE 95 in putty form has been found to produce excellent results. This product is a flexible rubber-like putty comprising urethane. The putty is mixed with equal portions of a hardener and forced into the primer pocket or primer cup at room temperature and allowed to set. The cast'product adheres to most other plastics and also to metal if a metal primer is first applied. The urethanes also flow into pores and interstices of the primer pocket for good adhesion.

The preferred polyurethane has the following characteristics:

TABLE Viscosity of mix at F 31,000 centipoises Experimentation with other plastics such as rubber, polyethylene and acrylics has indicated that they do not remain in the primer pocket well, are too brittle and have no elastic recovery in comparison with the polyurethanes. Brittle and hard plastics such as phenolics are totally unsuitable.

The polyurethane compositions can contain about 10% to 25% of rubber and some species of die rubber used in making copies of hollow molds can be used. Compatible mixtures of polyurethane and neoprene may be used. Other plastics having the foregoing characteristics can be used.

What is claimed is:

1. A dummy cartridge suitable for dry-firing practice comprising:

a cartridge case having a base end with a center fire primer pocket therein;

said primer pocket including a flash hole defined by said base end and a shock-absorbing plastic body molded within said primer pocket, characterized by its toughness and ability to recover after penetration by a firing pin;

an integral portion of said plastic body extending within said flash hole in interfacial locking relationship.

2. A dummy cartridge in accordance with claim 1 in which: said plastic body comprises polyurethane.

3. A dummy cartridge suitable for dry-firing practice comprising:

a cartridge casing having a center fire primer pocket;

said primer pocket including a flash hole; said primer pocket being filled with a shockabsorbing plastic body extending through said flash hole and characterized by its toughness and ability to recover after penetration by a firing pin. 4. A dummy cartridge in accordance with claim 3 in which:

said plastic body is characterized by a Durometer Shore A hardness of about to 120, a tensile strength of about 1,000 to 2,000 psi, an elongation of about 250 to 270 and a tear strength of at least about 900 to. 1,500 lb/in. 5. A dummy cartridge in accordance with claim 3 in which said plastic body comprises polyurethane having the following characteristics:

Durometer Shore A I Hardness Tensile Ultimate ASTM D4l2-5lT I500 psi (7 days) Elongation 100% Modulus Tear Strength Abrasion weight loss Specific gravity Shrinkage linear Viscosity of mix at 75F -Contimied tending into the flash hole of the primer cup.

ASTM D638-58T 265% 1000 psi (7 days) 400 lb/in (7 days) 0.1734

1.06 0.0003 in/in 3l,000 centipoises ASTM D41 2-5 lT ASTM D l004-59T

Claims

1. A dummy cartridge suitable for dry-firing practice comprising: a cartridge case having a base end with a center fire primer pocket therein; said primer pocket including a flash hole defined by said base end and a shock-absorbing plastic body molded within said primer pocket, characterized by its toughness and ability to recover after penetration by a firing pin; an integral portion of said plastic body extending within said flash hole in interfacial locking relationship.

3. A dummy cartridge suitable for dry-firing practice comprising: a cartridge casing having a center fire primer pocket; said primer pocket including a flash hole; said primer pocket being filled with a shock-absorbing plastic body extending through said flash hole and characterized by its toughness and ability to recover after penetration by a firing pin.

4. A dummy cartridge in accordance with claim 3 in which: said plastic body is characterized by a Durometer Shore A hardness of about 85 to 120, a tensile strength of about 1,000 to 2,000 psi, an elongation of about 250 to 270 and a tear strength of at least about 900 to 1,500 lb/in.

5. A dummy cartridge in accordance with claim 3 in which said plastic body comprises polyurethane having the following characteristics:

6. A dummy cartridge in accordance with claim 3 in which: said primer pocket includes a primer cup having said plastic body molded therein and with a portion extending into the flash hole of the primer cup.