Safety system for firearm

A safety mechanism to prevent the accidental discharge of a firearm such as an automatic pistol when the firearm impacts on a hard surface utilizes a second spring loaded slide bolt as an impact safety in addition to a conventional, trigger-activated spring biased slide bolt. The second safety bolt and its bias spring are structured and located so that an impact which causes the trigger-activated safety bolt to move out of its normal "safety-on" position also causes the second slide to move against its bias spring to engage a recess on a firing pin and thereby prevent the weapon from firing. Also, when the firing pin is located in a slide of an automatic pistol, the slide, firing pin and hammer are structured so that a movement of the slide on impact towards the hammer causes the rear edge of the slide to strike the hammer with the firing pin spaced from the hammer.

BACKGROUND OF THE INVENTION 
This invention relates in general to firearms and more particularly to 
safety mechanisms for automatic hand firearms. 
Safety mechanism to prevent the accidental discharge of a firearm are well 
known in the art. One type of safety is a bolt that slides transversely to 
the longitudinal axis of a firing pin and is adapted to engage a recess 
formed on the firing pin. The safety bolt is spring biased to engage the 
recess and thereby block a longitudinal movement of the firing pin. A 
safety release mechanism, activated when a trigger is pulled to fire the 
weapon, pushes the safety bolt out of the recess to release the firing pin 
just prior to firing. 
While such safety mechanisms are reliable during normal handling of a 
weapon, they can fail to prevent an accidental discharge of a shot when 
the weapon falls and strikes a hard surface or is otherwise subjected to 
an impact. More specifically, an accidental discharge is likely to occur 
when the weapon has an orientation on impact such that one component of 
the impact force drives the safety member out of the recess on the firing 
pin while at the same time a second component of the impact force drives 
the striking pin forward against a priming cap of a cartridge. The forward 
movement of the firing pin can be direct, or through a backward movement 
of a slide which carries the firing pin against the hammer. 
It is therefore a principal object of this invention to provide a reliable 
safety system that prevents the accidental discharge of a firearm due to 
an impact that releases another safety device that is normally positioned 
to block a forward movement of the firing pin. 
Another object of the invention is to provide an impact safety system that 
prevents the firing pin from striking the hammer through movement on 
impact of a slide carrying the firing pin. 
A further object of this invention is to provide a safety mechanism that 
achieves these objects while being rugged and having a relatively low cost 
of manufacture. 
SUMMARY OF THE INVENTION 
An "impact" safety bolt is provided that slides in a direction transverse 
to the longitudinal axis of a firing pin. A bias spring urges the impact 
safety bolt to a position that is clear of the firing pin during normal 
handling and use. The impact safety bolt and its bias spring are 
structured and oriented so that an impact that disengages a similar 
spring-biased main safety from its normal blocking position, and causes a 
longitudinal movement of the firing pin that can fire a cartridge, also 
drives the impact safety against its bias spring to engage a recess on the 
firing pin and block its movement. Preferably the safety bolts are slide 
pieces that move generally perpendicular to the firing pin. Also in a 
preferred form, the "main" safety engages a recess formed on an upper 
surface of the firing pin, and the "impact" safety engages a recess formed 
on a lower surface of the firing pin. In a firearm where the firing pin is 
mounted in a slide capable of movement towards the hammer, the slide, 
hammer and firing pin are structured and located so that the striking pin 
is spaced from the hammer by when a rear edge of the slide strikes the 
hammer. 
These and other features and objects of the invention will become apparent 
to those skilled in the art from the following detailed description to be 
read in light of the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIGS. 1-3 illustrate an automatic pistol which incorporates a safety system 
constructed according to the invention. The pistol has a frame 11 that 
mounts a slide 12, a catch lever 13 and a trigger 14. A barrel 15 is 
secured to the frame 11 by any suitable means such as a press fit. Within 
the slide 16 are mounted a firing pin 17 and two spring loaded safety 
bolts or slides 18 and 19 which act independently of one another. The 
firing pin has its longitudinal axis aligned generally in the direction 
indicated by the arrow B in FIG. 1. The safety slides 18 and 19 are 
movable in a second direction generally transverse to the longitudinal 
axis of the firing pin 17 and indicated by the arrow C in FIG. 1. 
The slide 16 is supported on the frame 11 so that the gas pressure 
developed when a round is fired causes the slide to move in the direction 
of the arrow B against the force of a recoil spring (not shown). This 
backward recoil movement of the slide is used to eject the cartridge case 
of the fired round and to cock the firing mechanism. When the slide 
returns to its forward position (FIGS. 1 and 2) it loads a new cartridge 
from a magazine (not shown) into the barrel. 
The trigger 14 is connected by means of a trigger arm 20 to the hammer 12, 
the catch lever 13, and a safety releasing lever 21 that acts on the 
safety bolt 18. The releasing lever 21 and the hammer 12 are mounted on a 
common axel 12a. 
In operation, as the trigger 14 is drawn to the rear to fire the pistol 
(the hammer 12 being cocked), the trigger arm 20 pushes the release lever 
21 upwardly which in turn pushes the safety bolt 18 upwardly out of a 
recess formed on the upper surface of the firing pin 17. After the trigger 
14 has moved through a predetermined distance, the releasing lever 21 has 
pushed the safety bolt 18 against the force of its bias spring, to a point 
where the bolt is clear of the recess in the firing pin. The firing pin is 
then released and ready to be driven forward by the hammer 12, against the 
force of a firing pin spring, to ignite the priming cap of the cartridge 
in the barrel. Further movement of the trigger allows the catch lever 13 
to move forward which in turn allows the cocked hammer 12 to strike the 
end of the firing pin and drive it forward. 
FIG. 1 illustrates a situation in which the pistol is likely to discharge 
unintentionally through an impact. The pistol has fallen vertically in a 
direction indicated by the arrow A and the weapon is in an oblique 
position with respect to the vertical so that the hammer 12 strikes the 
floor or a similar hard surface. In this situation, the impact of the 
hammer on the hard surface suddenly brakes the frame 11 and all the parts 
mounted on it. The slide 16, however, retains a moment of inertia which 
causes it to execute a backward sliding movement relative to the frame 11 
until it strikes the hammer. 
Since the direction of movement of the slide 16 is not aligned with the 
direction of fall of the pistol, the force of the impact has a component 
in the direction of movement of the slide (arrow B) and a component at 
right angles to this direction (arrow C). Provided the weapon is dropped 
from a sufficient height, the component of force in the direction of the 
arrow C can be sufficient to throw the safety bolt 18 in an upward 
direction, that is, in the direction of the arrow C, in opposition to its 
bias spring. This movement on impact therefore moves the safety bolt 18 
out of its normal blocking position and releases the firing pin. The 
firing pin, however, does not move forward to fire the cartridge because 
the component of force in the direction of the arrow C also simultaneously 
moves the "impact" safety bolt 19 into a blocking position in which it 
engages a recess formed on the lower side of the firing pin. The second 
safety bolt 19 therefore prevents a movement of the firing pin and an 
accidental discharge of the pistol due to the impact. 
In addition to the action of the "impact" safety bolt 19, it is desirable 
to structure the slide, firing pin, and hammer so that the backward 
movement of the slide following an impact causes the front face 23 of the 
hammer to strike the edge 24 of the slide and not the rear end 25 of the 
firing pin. Given the substantially flat configurations of the striking 
surface 23 of the hammer and the end surface of the slide 16, this action 
can be achieved by designing the catch notch 22 on the hammer so that the 
front face 23 of the hammer is inclined with respect to the end surface of 
the slide. Accordingly the angle of inclination should be such that the 
edge 24 of the slide strikes the surface 23 before the end 25 of the 
firing pin strikes the surface 23. 
Although the invention has been described with reference to an automatic 
pistol, it will be understood that it can be employed in other weapons 
where a safety member can move out of its blocking position due to a 
sudden impact. Further, although the invention has been described with 
respect to safety members in the form of spring-biased slide bolts, it 
will be understood that other safety members having a different 
configuration or mode of movement can be employed. These and other 
modifications will become apparent to those skilled in the art from the 
foregoing description and the accompanying drawings. Such modifications 
are intended to fall within the scope of the appended claims.