US2167828A - Bird shot - Google Patents

Description

Patented 1, 1 939 amp snow: Ralph L, Dowdell, St. Paul, and Robert G. Green,

' Minneapolis, Minn.

assignors to Regents of the University. of Minnesota, Minn., a corporation of Minnesota Minneapolis,

No Drawing. Application July 19, 1935,

Serial No. 32.213

8 Claims.

This invention relates to new and useful improvements in metallic shot and the method of making it. I

More particularly-the invention relates-to shot formed of an alloy containing a large proportion 'of lead and which novel shot is adapted to more has long been" the-subject matter of research, I

and it has been proved that lead poisoning in water fowl has its origin in the large quantity 20 of expended shot that from yearito year is deposited in the water and mud adjacent shooting points and blinds in marshes, shallow baysand lakes. The action of water or moisture upon.

lead shot is so slow as to be inappreciable and 25 leadsto the conclusion that shot pellets last for many years. Many birds find and-swallow these leaden pellets while searching for food in the same manner that they swallow gravel, seeds or other small hard objects. These leaden pellets pass to the gizzard along with pther small hard objects such as gravel, which are necessary for the propergrinding or trituration of food. The shot accumulates in the gizzard of' the tow] day by day andbeing only slowly ground away'by 35 attrition induces lead poisoning of the fowl. I One phase of this novel invention is directed to the production of lead shot which are com-- paratively readily decomposable in the presence .e' of moisture. -.That is, the novel shot-may be so 40 made that, missing the bird at which they are fired, they drop to the lake or moistground and decomposition immediately starts; or, if quickly 1 picked up by a bird, the inoisturein the bird's sizzard combined with its natural grinding ac- *5 tion' quickly disintegrates the pellet. and it quickly passes joutwardly through the bird's in- .testineswithcut appreciably afiecting the bird.

In accordance with-the teaching of this novel invention, {such ,a shot ms. 50 means of a lead alloy.

comparatively readily disintegratable. in ordi- -."nary water is formed by treating lead in its molten or. powdered states with other metals which are anodic to it in the electromotive force (series of metals. A shot formed of such a lead be produced by A leadshot which is alloy may disintegrate by electrolytic or galvanic action inan electrolite of natural waters within a period of. less than two months, Thus, .such a shot canbe produced by an alloy containing not less than 90% of lead by weight '5 with not more than of magnesium, barium, .zinc, lithium, sodium, potassium, or calcium.

Such an alloy of lead shot is decomposable in water to produce a relatively soft residue of flakes or powder which wild fowl will noteat 10 Preferably the alloy metal is one having a.

relatively high specific gravity or, if the alloy metal has a low specific gravity, a smaller amount must be efiective because the resultant alloy shot must have the ballistic properties and substantially the trajectory of lead shot.- As an example oflthe invention, a commercially inexpensive novel" alloyshot may be composed of approximately ninety-six per centum (96%)- by weightof lead and approximately four per centum (4%) by weight of magnesium.

Another example of a practical *shot is an alloy comprising approximately ninety. per centum -(90%.) by weight of lead with approximately ten per centum (10%) by weight of either magnesium, zinc, lithium, sodium, barium, potassium or calcium. The above proportions are. in no sense critical but-can be varied over wide limits depending upon the rate of disintegration desired. For example the amount of. l'ead in the shot may constitute anywhere from 90% to '99 of the total weight of the shot, as desired. Preferably the amount of lead should range from 96%, to 99% of the total weight of the shot. Reduced percentages of lead cause reductioninspecific' gravity or density of the shot which is undesirable from the ballistic standpoint, whereas if higher percentages of lead are used thejrate of disintegration. is corresnond- 'ingly reduced.

In the case of such alloy shot the electrolytic 40 or galvanic action in the presence of moisture forms hydrogen and hydroxyl ions thus accelerating its*decompojsition. An advantage inherent 'in shot made inaccordance with this invention. is the reaction in thegizzard of birds, such' for example, as wild ducks; X-ray photographs of a duck fed several lead-magnesium alloyshot, for example, conclusively show that the combination of the gizzard-grinding action and the "moisture immediately starts the decomposition of the shot. Within a few minutes after ingestion of the novel shot by the bird the reduction of the shot by the trituration processes of the gizzard'. commenced and particles began their course throughthe intestinal tract and withina few hours the-shotmaterial was evacuated. The bird one of thenovel shot fired at it, the shot will become embedded in the-moist flesh of the bird.

Hence, if the bird is not eaten by the hunter reasona-bly soon thereafter but is placed in storage and subsequently eaten, it may be found that the moisture of ,the bird's flesh has provided the necessary electrolyte to start the reduction of the alloy shot to powder or flaky form with the result that some may beeaten by the hunter instead of prompt removal from the mouth of the hard lead shot as is common.

Therefore, the invention further comprehends the coating of the novel alloy shot. Such coating'is preferably one that is relatively impervious to moisture so that when fired and embedded in the bird's flesh it will remain in its initial hard state, yet, may be comparatively quickly worn I through by the grinding action of the bird's gizzard to permit access of moisture to the alloy shot whereby it may be quickly disintegrated and I evacuated.

Such coating or covering may consist of a thin layer of a metal such as copper or cadmium or a non-metallic coating such as lanolin which is a fatty substance extracted from wool and is commonly used as a basis for ointments'. This substance has as one of its characteristics the property of being rather tenaciously adherent to other materials. The metallic, coating 'ofthe novel shot prevents the moist 'ilesh of the bird (when the shot is embedded'therein) from d8! composing the shot and the same phenomena istrue of the adherent lanolin but when the coated novel'shot are ingested by the bird, the natural winding action oi' the gizzard quickly wears ofl the metallic or non-metallic coating or layer and causes prompt access of gizzard moisture to the alloy shot and decomposition thereof proceeds. It is to be understood that the novel alloy shot not, only becomposed of lead with a single substance which is anodic to lead-in the electrofmotive force series of the elements but may also be composed of lead and two or more of such,

anodic substances. In cases of the use of more than one alloying'substance, it is deemed prefer-- able to employ approximately ninety per centum (90%) by weight of lead and approximately ten per centum (10%) by weight of the alloying substances. Furthermore, in such cases, better resultsseem tobe securedbyusingtwotofourper centum byweight of mum with the bal--, ance of the ten per centum of alloying material of the other alloying substances. Thus, for e xample, if it be desired tov make the specific gravity of the completed shot greater, one may use more zinc proportionately to the magnesium.

Thus, the process or method of forming these novel shot is to employ lead as the major porless than two percent.

gration when imbedded in'the flesh of a fowl.

tion thereof and next preferably reduce the lead to a molten state and then add the selected alloying materials which are anodic to the lead in the electromotive force series. This alloy mass is then inexpensively formed into shot by'the old shottower dropping process long well-known in the shot-forming art. As a further step in this methd, the alloy shot thus formed and" cooled may then be treated with a very thin layer of copper, cadmium or other metal frequently used in the :coating of shot or with a non-metalliclayer of lanolin or substances of similar characteristics by dipping or immersing the formed alloy shot in such substance preferably in a viscous or liquid state.

Itis to be understoodthat the construction of the novel shot as an article-of manufacture and the method or process of forming it as disclosed herein is illustrative but not restrictive and that they may be modified within the meaning and scope of the claims which follow.

Having thus described our invention, what we claim as new, and desire to secure by Letters Patent, is:

We claim as our invention: v

1. A shot consisting of an alloy of approximately ninety per centum by weight of lead and approximately ten per centum by weight of a material adapted to accelerate the decomposition of such alloy shot in the presence of moisturex '2. An alloy-shot consisting of approximately ninety per centum by weight of lead alloyed with magnesium having approximately two to four per centum by weight and approximately eight to six per centum by weight of other substances to form an alloy shot which will dissociate water to 'form' hydrogen and-hydroxyl ions upon submergence in electrolytes and thereby accelerate the disintegration of the alloy shot.

3. A shot comprising an alloy of lead with met- I als which are anodic to lead in the electromotive series of metals, including magnesium in an amount not substantially less than one percent by weight.

4. A shot comprising an. alloy of lead with a metal which is anodic to lead in the electromotive series of metals, said metal being present in a quantity not substantially less than two percent. ,5. Ashot composed only of lead and magnesium,

the amount of magnesium not being substantially H 8. 'A metallic shot comprising an alloy of approximately '96% by weight of lead and approximately 4% by weight of magnesium. e 7. A shot comprising an alloy of lead and mag nesium, the magnesium being in an amount not substantially less than 1% by weight.

8. A shot comprising an alloy of lead and mil-8- nesium, the magnesium being in an'amount not substantially less-than 1% by weight, and a covering relatively impervious to moisture but adapted to be removed by triturating action of the 'gizzard of a fowl and proof against rapid disinte- RALPH L. nowDEnL. ROBERT-G. cam.-