Ammunition and explosives – Cartridges – Case
Patent
1993-10-18
1996-08-27
Lovering, Richard D.
Ammunition and explosives
Cartridges
Case
102467, 523126, 523128, F42B 530, F42B 706
Patent
active
055490484
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
This invention relates to cartridge cases for shotguns.
The traditional shotgun cartridge comprised a cartridge case made out of a paper tube with a paper base wad and a brass or steel head together with explosive powder, a fiber wad and lead shot. The end of the paper tube was closed by either forming a fluted crimp or inserting a cardboard disc which was held in place by a rolled turnover.
The components described above were all degradable because they were either made from cardboard or paper or were made of organic materials and steel which corrodes.
The invention of plastics and the accompanying technology enabling accurate extrusion of plastic tube revolutionised the shotgun cartridge component industry. The paper tube was replaced by a plastic tube made from extruded thermoplastic synthetic resin polyethylene, the base wad was made from injection moulded polyethylene and the piston wad was made from injection moulded polyethylene. The result of these new materials was a cheaper shotgun cartridge which was more consistent in ballistic performance than the original paper based product. The drawings of our WO 91/05982 illustrate this more modem cartridge.
The synthetic resin (plastics) materials have however led to an environmental problem because the plastic cartridge casing (1 in the drawings mentioned above) after firing, is ejected from the gun and is left lying on the ground where it will remain for an almost indefinite period. The plastics piston wad is also projected from the gun upon firing and falls to the ground once again remaining for an indefinite period. WO 91/05982 deals with this problem and provides an improved and biodegradable wad.
Discarded plastics products are an environmental pollutant insofar as they are being introduced into the environment at a greater rate than they are removed by natural forces. The present invention uses additives for the plastics which convert the normal polyethylene tube constituting the cartridge case and extruded on standard production machines into an article which after firing will degrade by the action of bacteria and fungi and optionally also by the action of light. The cartridge case in accordance with the present invention should biodegrade and be removed from the environment at a greater rate than it is being introduced by the use of shotguns. The new case therefore is a considerable advance over the previous non-biodegradable cases from the point of view of environmental pollution.
Earlier patent specifications have proposed various additives which have modified plastics to render them photodegradable. Other additives have been proposed which create biodegradable plastic materials for general use. However, there has been no product until this present invention which has brought together the properties of biodegradation and photo-degradation to extruded plastics which have relatively thick cross-sections such as the components used for shotgun cartridges. By thick we mean of the order of 2 to 3 mm as opposed to films whose thicknesses may be measured in microns. The previously proposed materials have tended to be unsuitable for shotgun cartridge cases because degradation has taken place spontaneously and gradually from the moment the plastic is manufactured, whereas the case according to the present invention remains stable until the shotgun cartridge is fired. The firing of the shotgun cartridge initiates the degradation process thereby making the product safe to use and predictable.
According to the present invention there is provided a shot-gun cartridge case made by extrusion or equivalent pressure forming process of a synthetic-resin based composition said composition containing bio and or other degradants but being stable in the thick-wall form until the cartridge is fired.
Thus the present invention provides a shotgun cartridge case formed from a plastics rendered potentially degradable by one or more additives, the plastic being stable until the gun is fired but thereafter becoming environmentally degradable. The degradation i
REFERENCES:
patent: 3103170 (1963-09-01), Covington, Jr. et al.
patent: 3147709 (1964-09-01), Werner
patent: 3722412 (1973-03-01), Herter
patent: 4017469 (1977-04-01), Nicoud espouse Le Brasseur
patent: 4931488 (1990-06-01), Chiquet
Chapman Graham
Godfrey-Phillips Arthur H.
Lovering Richard D.
The Kent Cartridge Manufacturing Company Limited
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