Amusement devices: games – Aerial projectile game; game element or accessory therefor... – Projectile backstop
Patent
1996-03-13
1996-10-15
Shapiro, Paul E.
Amusement devices: games
Aerial projectile game; game element or accessory therefor...
Projectile backstop
F41J 112
Patent
active
055647120
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a bullet trap for indoor shooting, which trap significantly reduces the distribution of lead contaminated dust that is connected with indoor shooting.
Among shooters it is commonly known, that considerable amounts of lead contaminated dust is set free upon shooting and accordingly mixed with the air. The problem is of course particularly apparent in connection with indoor shooting, where the amount of lead in the breathing air can be large enough to be detectable in the shooter's blood. This danger to the health is so obvious and substantial that limitation of gun training have been discussed and also realized.
The lead particles that are set free upon shooting arise mainly from two sources: partly from the cap charge, which is believed to produce 30-40% of the distributed lead, partly from the bullet, which produces 60-70% of the lead.
At the firing moment, a certain amount of lead is detached from the back end plane of the bullet, where the bullet usually has no jacket and is subjected to high pressure and hot gases as it is pushed through the bore. This problem is sufficiently solved by attaching a separate plate to the end plane, which plate is folded over by the surrounding jacket, or by electrolythically applying a jacket material. The major distribution of lead particles arise when the bullet hits the bullet trap, where the bullet is splintered and detached from its jacket.
Conventionally, the bullet trap comprises a vertically standing steel plate, with a thickness of 10-15 mm, in front of which a curtain made of synthetic fibres or rubber is suspended to prevent ricochets from the steel plate. The bullet penetrates the curtain and is subsequently splintered against the plate. Through the contractibility of the material in the curtain, the bullet will only leave a very small hole in the curtain. However, the curtain has no ability to shield the shooting range from the lead contaminated air, which exists in the space between the curtain and the steel plate. Due to the generation of heat, caused by the impact of the bullets with the plate, and due to the turbulence that is caused by the velocity of the bullet, a considerable air circulation is produced behind the curtain, whereby this air strives to pass the curtain through openings at the floor, the ceiling and the sides of the curtain.
Among attempts to reduce the amount of lead in the air reference is made to the procedure of suspending multiple curtains behind each other. Since each curtain contributes to the retardation of the bullet, it has lost sufficient energy not to splinter at the impact with the plate. The drawback of this solution is that it is very costly, because all curtains must be simultaneously replaced when the target area has received enough bullets to reduce the retardation effect.
Another solution to the problem is to install, behind the targets, a backwards tapering funnel of steel, with a circular drum connected to its back end taper. The bullets are trapped within the wide opening of the funnel, bounces backwards to the drum where they rotate till they have lost their energy, where upon they fall out of the drum, and are collected, comparatively undamaged. On the inside, the funnel is sprinkled with water or oil spray to produce a lubricating effect that will spare the funnel and the drum and to flush the bullets out of the bullet trap. The draw back of this solution is likewise the great costs and the funnel also requires a large installation space which precludes the utilization of the funnel in most existing shooting premises.
To reduce the amount of lead particles in the air, the present invention provides a device which readily can be installed in existing shooting premises through being space saving, and which is not associated with above said great costs for replacement of curtains for the bullet trap.
Briefly, the invention includes forming of a closed space between the curtain and the steel plate, and connecting the closed space to a device for continuous evacuation and dust separati
REFERENCES:
patent: 4164901 (1979-08-01), Everett
patent: 4317572 (1982-03-01), Iseli
patent: 4773653 (1988-09-01), Unverzagt
patent: 4818946 (1989-04-01), Kahler
patent: 4856791 (1989-08-01), McQuade
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