Bullets for fire arms

The invention relates to a bullet for a portable fire arm of a caliber between 5 and 12 mm. This bullet is formed by a solid homogeneous monobloc piece, made from copper or a copper alloy, having the outer form of a cylinder of revolution connected along a sharp edge to a cone of revolution whose angle at the apex is equal to 60.degree.. The preferred application is for close attack and defense hand weapons.

This invention relates to small calibre bullets or projectiles for portable 
fire arms, said calibre being between 5 and 12 mm and preferably of the 
order of 9 mm. 
It relates more particularly, among these bullets, to those whose outer 
surface is in the form of a cylinder of revolution connected along a sharp 
edge to a coaxial cone of revolution whose angle at the apex is between 
50.degree. and 80.degree., this angle being preferably of the order of 
60.degree.. 
It relates also to cartridges equipped with such bullets. 
Known bullets of this kind have a very low density, preferably between 1 
and 3 g/cm.sup.3, for which said bullets are generally formed from a light 
material (polymer or magnesium) and are hollowed out axially for receiving 
a medicament or a vaccine : the purpose of the bullets in question is in 
fact to implant medicaments in the flesh of living animals without 
seriously injuring these latter, the firing of said bullets being effected 
at subsonic speed. 
The bullets of the invention answer a different purpose : they are intended 
to be fired at supersonic speed by means of hand or shoulder weapons, in 
particular by means of automatic pistols and it is desired to obtain with 
them relatively destructive impact effects at close range, while reducing 
their harmfulness at long range as well as their cost price. 
To this end, the bullets in question, having the above defined outer 
shape--and not one of the cylindro-ogival shapes without a sharp angle 
generally known for dense metal bullets--, are characterized in that they 
are formed by a solid homogeneous monobloc piece made from copper or 
copper alloy. 
In preferred embodiments, recourse is had to one and/or the other of the 
following arrangements: 
the axial length of the cylindrical zone of the bullet is less than that of 
its conical zone, the first being preferably of the order of 5 mm for a 
calibre of 9 mm, 
the bullet is enveloped in a thin film of silicone. 
The invention comprises, apart from these main arrangements, certain other 
arrangements which are preferably used at the same time and which will be 
more explicitly discussed hereafter.

The bullet in question, designated generally by the reference 1 in the 
drawing, is formed of a monobloc piece made from copper or a copper alloy 
defined outwardly, in its rear half, by a cylinder of revolution 2 and, in 
its front half, by a cone of revolution 3 connected to cylinder 2 along a 
sharp edge 4. 
The point 5 of the cone 3 is not blunt : it remains pointed in this sense 
that its contour is defined outwardly by a sphere with a radius at most 
equal to 0.5 mm. 
The angle at the apex of cone 3 is between 50.degree. and 80.degree., being 
preferably equal to 60.degree.. 
The axial length L.sub.1 of the cylindrical rear zone is less than the 
axial length L.sub.2 of the front conical zone 3 : this length L.sub.1 is 
for example 5 mm for a calibre of 9 mm and a length L.sub.2 of the order 
of 8 mm. 
The bullet thus described is very light : it weighs only 4 to 5 grammes 
instead of 8 grammes for the usual bullets of the same calibre. 
In a way known per se, this bullet is coated with a thin film 6 (FIG. 2) 
formed of a "lubricating" material facilitating the sliding of the bullet 
into the barrel of the weapon and its penetration in the air and in 
solids, a material formed particularly by a silicone or a fluorated 
polymer. The thickness of this film is some tens of microns 
The above bullet is fitted in the usual way in the mouth of a case (not 
shown) charged with explosive to form a cartridge : because of the 
relative lightness of said bullet, this explosive is here a specially 
quick-burning powder of the kind used in the manufacture of cartridges for 
supplying certain rapid fire hunting weapons. 
Experience shows that the conicity of the front pointed end of the bullet 
facilitates the automatic loading of the cartridge instead of making it 
more delicate, as may be at first feared : in fact, the semi-angle at the 
apex of this cone is generally greater than the slope of the feed 
mechanism with respect to the axis of the barrel, so that, even if the 
breech is sharply closed, there is no risk of "battering" the front 
surface of the bullet against the internal wall opposite this breech, 
battering which could cause jamming; such a closing of the breech ensures 
on the contrary in every case a correct tilting of the short and pointed 
cartridges fitted with bullets of the invention. 
The firing of such a bullet leads to the following findings : 
because its weight is substantially half the weight of the usual comparable 
bullets, its starting speed is about twice as high as the starting speed 
of said usual bullets : this speed is then clearly greater than the speed 
of sound and particularly of the order of 550 to 600 meters per second, 
moreover, the presence of convex angular zones (sharp edge 4 and point 5) 
on the outer surface of the bullet causes, at the high firing speed 
indicated, the creation of shock waves which, at impact, create an 
explosive effect (a phenomenon known under the name of "hydraulic 
compression" and "cavitation"). 
In other words, the impact of such a bullet fired at close range at a 
living being (man or animal) causes a relatively serious wound by bursting 
the flesh. 
On the other hand, because of its lightness, the bullet in question loses 
its speed and so its energy over a shorter distance than the usual bullets 
of the same calibre and becomes practically inoffensive at long range or 
after passing through a first obstacle. 
In other words, the efficiency of firing at point blank or at a close 
object is increased, whereas on the contrary the danger of "lost" bullets 
is decreased, which constitutes a dual advantage for a large number of 
applications. 
The reduction of the individual weight of the bullets considered, as well 
as the simplification of their manufacture, because of their homogeneous 
construction, lead furthermore to a reduction in price. 
Of course, the bullets in question may be used for other firing than that 
for close defence or attack, for example for testing the resistance of 
certain materials to impacts, perforations... 
Following which, whatever the embodiment adopted, there is finally provided 
a bullet for portable fire arms whose construction and advantages 
(particularly the increased efficiency at close range, the reduced danger 
at medium range or at long range and the economy) follow sufficiently from 
what has gone before. 
As is evident, and as it follows moreover already from what has gone 
before, the invention is in no wise limited to those of its modes of 
application and embodiments which have been more especially considered; it 
embraces, on the contrary, all variations thereof.