Firearm safety lock

A safety lock is described for weapons in which the safety lock includes a rigid housing 20 enclosing a hammer spring 27 and plunger 28. The plunger 28 receives an end of a hammer pin 34 either supplied with the weapon, or the present lock 19. The hammer pin is received through an opening at the top end of the rigid housing 20 to engage and press axially against the plunger 28. The plunger 28 includes a plunger shaft 31 that extends along the spring axis through the spring to a rotatable cam 37 (62) which may be selectively moved by a lock assembly 47 to shift between a position in which a recess is aligned with the plunger, thereby allowing the plunger to move axially and permit operation of the weapon, or to position a lock surface 40 in alignment with the plunger, for abutting the plunger and successfully locking the plunger in position so the associated hammer pin and hammer may not be operated.

TECHNICAL FIELD 
The present invention relates to safety devices for firearms and more 
particularly to such devices that selectively prevent hammer operation in 
such firearms. 
BACKGROUND OF THE INVENTION 
There has been a constant need for safety devices in firearms to prevent 
accidental discharge. There is also a growing need to disable firearms to 
prevent intentional use of the firearms as when such firearms are stolen. 
To this end, various locking devices have been developed to lock the 
firearm trigger mechanism and thereby prevent operation of the firearm. 
For example, various devices are available on the market that will connect 
to the trigger housing of a firearm, locking the housing against access to 
the firearm trigger. However, such apparatus must be mounted to and 
removed from the firearm. The firearm is not disabled by the locking 
device but is simply rendered inoperable while the locking mechanism is in 
place on the trigger guard. Thus, a relatively simple operation with a 
hand drill or saw will facilitate removal of the lock and leave the 
firearm in operable condition. Further, such mechanisms, since they are 
removable from the firearm, are easily misplaced and lost. 
It is therefore desirable to provide some form of locking mechanism that 
may be either integrated with the firearm or retrofitted to existing 
firearms that will remain with the firearm and that will disable the 
firearm completely both in the locking condition and if the locking device 
is removed from the firearm. Several devices have been patented that 
represent attempts to fill the above need. 
U.S. Pat. No. 4,384,420 to Von Muller discloses a magazine lock for 
firearms. This device replaces the magazine of "clip" type firearms for 
purposes of locking the magazine. The lock does not carry ammunition and 
is not a permanent fixture on the weapon. When the weapon is in use, the 
lock must be removed. This apparatus is therefore somewhat similar in 
utility to the trigger guard locks discussed above. 
U.S. Pat. No. 3,882,622 to Perlotto discloses a locking device to lock a 
weapon safety latch mechanism into position. The device requires a key to 
operate the weapon. The locking device is fitted into the weapon body and 
requires extensive tooling unless the weapon is manufactured with the lock 
in place. 
U.S. Pat. No. 3,735,519 to Fox discloses a locking device that prevents 
movement of the weapon's safety to a firing position. This is said to 
prevent the weapon from firing. The lock includes a combination tumbler 
requiring that the proper combination of numbers be arranged to disconnect 
the lock and allow the sear to pivot away from the bolt and thereby enable 
the bolt to move. This device, again, must either be manufactured with the 
weapon or would require extensive modification of the weapon for retrofit 
installation. 
U.S. Pat. No. 4,763,431 to Allen discloses another form of combination lock 
device that mounts to the hand grip mechanism of a firearm. This mechanism 
is utilized to lock the firing mechanism until a prescribed number 
sequence is pushed into the handle-mounted push button system. The 
apparatus is extremely complex and bulky with numerous mechanisms and 
backup mechanisms used to lock the operating elements of the weapon. 
U.S. Pat. No. 2,994,981 to Carrigan discloses a locking device that is 
built into the hand grips of a revolver for the purpose of selectively 
locking out the hammer function. As with many other devices, the lock is 
used simply to temporarily lock the hammer mechanism which, otherwise, 
will operate freely. If drilled through, the locking device will become 
inoperable and allow the weapon to function normally. 
U.S. Pat. No. 3,673,725 to Cravener discloses a useful locking arrangement 
using a key device which selectively positions a hammer rod obstruction 
into the rearward path of the weapon's hammer. The obstruction will 
successively prevent the hammer from being withdrawn and will therefore 
operate as an effective safety device. However, the device may be removed 
from the weapon, and leave the weapon completely operable. 
U.S. Pat. No. 3,553,877 to Welch discloses a firearm safety device that 
makes use of a key lock mechanism and actuator arm for shifting a lever 
into position preventing movement of the weapon's safety from the safe to 
the fire position. Like Cravener, this apparatus is functional to the 
degree that it will operate when in proper position within the weapon. 
However, when the device is removed, the weapon is free to operate in a 
normal manner. 
International Patent Application WO82/02941 (PCT/EP82/00070) discloses a 
security device which includes a bolt obstruction that is pivoted into 
position by a toggle mechanism. Once again, removal of the locking 
mechanism will permit free operation of the weapon. 
U.S. Pat. No. 4,136,475 to Centille discloses a safety device for firearms 
including a key operated lock. The lock releases a locking pin that, when 
shifted to a locking position, prevents the firearm trigger from 
operating. The device makes use of a rack-and-pinion gear linkage 
activating member with a locking pin movable responsive to operation of 
the rack-and-pinion linkage to slide into engagement with the trigger 
seat. It is assumed that, since the disclosure relates only to the trigger 
seat, removal of the locking mechanism would permit free operation of the 
weapon. 
U.S. Pat. Nos. 667,051 and 633,939 to Ackerman both disclose locking 
devices for shotgun "brake" levers. Operation with a key selectively moves 
a pin into position within a socket in the brake lever to lock the brake 
lever in position and thereby prevent the weapon from being opened. To 
disable the locking device, a simple procedure may be utilized to simply 
remove the locking pin. Operation of the weapon can then be accomplished 
in a normal manner. 
The above references clearly disclose the long felt need for locking 
devices for firearms to prevent their unintentional use, and in some 
cases, their intended use by undesirable parties. However, these apparatus 
do not provide a totally effective solution. Most, if not all, may be 
fairly easily disabled to facilitate operation of the weapon in a normal 
manner. Others are extremely complicated and would add significantly to 
the cost and maintenance of the weapon. Still others are complex in 
operation and may not be reliable. The need has therefore remained for a 
simple, effective, and reliable safety device for firearms in which a 
locking mechanism is provided to prevent operation of the firearm and 
dismemberment or attempted removal of the locking device will result in 
further disruption of the firing mechanism for the associated weapon.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
This disclosure of the invention is submitted in furtherance of the 
constitutional purposes of the Patent Laws "to promote the progress of 
science and useful arts" (Article 1, Section 8). 
The present invention is provided for utilization with a number of 
different weapons. Several firearms are designated in the drawings by the 
reference numeral 10 to generally indicate the broad utility of the 
invention. While these firearms are shown specifically, it should be 
understood that the present device may be utilized with numerous other 
forms of firearms, including shotguns (both hammer and hammerless types) 
and other weapons that will be clearly understood that may be utilized 
with the present safety devices. 
In general, the generic firearm 10 will include a hammer 11 mounted within 
a firearm frame 12 for actuation by a trigger 13. For general information, 
a single-action revolver is shown 15 in FIG. 1; a semiautomatic type 
pistol is shown at 16 in FIG. 14; and a portion of a "lever action" rifle 
is shown at 17 in FIG. 17. The above weapons 15, 16, 17 are simply 
exemplary of the generic firearm 10, it being understood that others may 
be utilized as indicated above. 
The present firearm safety lock is generally indicated in the drawings by 
the reference numeral 19. The present safety lock may be provided in 
different configurations or embodiments to adapt to various firearms 10. 
However, all embodiments include similar elemental features described 
below. 
The safety lock 19 generally includes a rigid housing 20 for securing a 
hammer spring 27 in place in an inaccessible manner. To this end, the 
rigid housing 20 includes a tubular member 21 covered at one end by a top 
plate 22. The top plate 22 is affixed as by welding or other permanent 
securing means to the tube 21. Plate 22 includes an opening 23 formed 
therein. 
The opposite end of the tube 21 includes a bottom block 24 for receiving 
the locking mechanisms to be described below. 
The entire housing 20, including the tube 21, bottom block 24, and top 
plate 22, is intended to be provided substantially as integral components 
to provide a secure and inaccessible storage and support frame for an 
enclosed hammer spring 27. 
The hammer spring 27 is enclosed within the housing for resilient 
deflection along a spring axis. It is advantageous that the hammer spring 
be a helical compression spring. The compression spring may be selected as 
compatible with the forms of springs currently used for driving hammer 
pins in hammer type weapons. The resiliency of the spring may be 
selectively adjusted either by substitution with various forms of other 
springs to accommodate the requirements of weapons to be utilized 
therewith, or may be adjustable as by shim stock, adjusting screws, etc. 
(not shown). 
It is the intent that the hammer spring 27 be selected to replace the 
existing spring mechanism in existing weapons such that the original 
hammer spring may be discarded and that the present locking arrangement be 
placed into position within the weapon as exemplified in FIGS. 8, 9, 14, 
and 17. 
In weapons manufacturing situations, the present locking arrangement will 
be assembled with the weapon and therefore not require removal and discard 
of an existing spring. 
A plunger 28 is movably received within the rigid housing 20. Plunger 28 
includes a headed end 29 that receives an end of the hammer spring 27. It 
also includes an outwardly facing recess 30 that is preferably aligned 
with the top plate opening 23 and coaxial with the spring axis. Headed end 
recess 30 is utilized axially to receive an existing or provided hammer 
pin 34. 
The hammer pin 34 is shown in FIGS. 8 and 9 connected to the present safety 
lock 19 and independently in FIG. 3. It is pointed out that various hammer 
pins may be utilized with the present invention. For example, a hammer pin 
or pins may be supplied with the present safety lock as an element of a 
retrofit package. Alternatively, the existing hammer pin manufactured with 
the weapon may be utilized. In either instance, the hammer pin will 
include one end 35 for selectively engaging the weapon hammer or hammer 
actuator, and a remaining end 36 engaging the plunger 28. This 
combination, with the releasable, somewhat articulated fit between the 
hammer pin 34 and plunger 28 will be useful in most instances as there may 
be some angular disparity between the axis of the spring when mounted in 
the weapon, and the line or arc of movement for the hammer pin. In other 
instances, it may be quite feasible to integrate the plunger and hammer 
pin as a single unit. 
A cam 37 is mounted within the bottom block 24. In a preferred 
configuration, the cam 37 includes a circular cam block 38 with a recess 
39 formed therein that is movable to an unlock position to allow the 
plunger shaft to act against and deflect the hammer spring 27. This 
position is identified in FIGS. 4, 5, and 6 in sectional views. FIG. 4 
shows the spring deflected and the plunger 28 received with the recess 39. 
This position would correspond to a "cocked" condition of the hammer as, 
for example, shown in FIG. 9. The unlocked, ready to cock orientation is 
shown in FIGS. 5 and 6. These positions reflect the unlocked position 
which enables normal usage of the associated firearm 10. 
The circular cam block 38 also includes a lock surface 40 formed therein. 
Surface 40 is shown rotated to in an operative position in FIG. 7 and in 
an inoperative position in FIGS. 4 and 6. The lock surface is 
substantially semicircular, formed on the rotational axis of the circular 
cam block 38. The surface 40 may be selectively rotated into the locking 
orientation shown in FIG. 7 by simple rotation of the cam block 38. 
Surface 40 at that time obstructs axial motion of the plunger 28 and 
thereby prevents compression of the spring 27. The spring 27 is thereby 
selectively locked out of operation. Furthermore, the plunger 28 and 
hammer pin 34 become rigidly connected to the weapon frame 12 to prevent 
motion of the hammer to a cocked position. The weapon is therefore 
completely locked from operation. 
The circular cam block 38 is permanently rotatably mounted within the 
bottom block 24 by provision of a cover 43 on one side of the block and by 
a lock mechanism housing 46 on the opposite side. These elements are 
welded or otherwise permanently secured to the lock device to prevent 
access to and removal of the cam block 38. 
The cam 37 is selectively shifted between the locking and unlocking 
positions by a lock means generally shown at 47. Lock means 47 is mounted 
to the lock mechanism housing 46 with an operator or actuator 48 engaging 
the cam 37 to rotate the cam 37 and selectively shift its recess 39 or 
lock surface 40 into position with respect to the plunger 28. The lock is 
preferably key operated. However, other forms of conventional locking 
mechanisms may be utilized as well. 
A preferred lock mechanism is the 720 model distributed by Lock America of 
7251-M Garden Grove Boulevard, Garden Grove, Calif. The above mechanism 
may be installed with little alteration securely within the lock mechanism 
housing in a permanent manner so the entire lock 19 becomes an integrated 
unit. 
The configuration of the assembly shown in FIGS. 2-9 and 17 is such that 
the unit may be easily installed within existing firearms to replace the 
existing hammer spring, whether it be a compression type helical spring, 
or a leaf type spring as typically found in revolvers. The configuration 
is such that the unit may be simply slipped into place where the prior 
spring was positioned and releasably held within the firearm frame. The 
hammer pin 34, whether existing or supplied, is easily fitted to the 
hammer in the usual manner. The device is therefore retrofitted to a wide 
range of existing firearms without requiring modification of the firearm 
structure. 
Addition provision may be made to prevent access to the lock 19 when 
secured in the operative, locked condition. This arrangement is 
illustrated in FIGS. 10-13 in which a modified version of the lock 19 is 
shown including a grip locking dog 57 (FIG. 13). The dog 57 is simply 
comprised of an arm extending outwardly from the internal circular cam 
block. The grip locking dog 57 therefore will selectively rotate as the 
internal cam block rotates responsive to rotation of a key. 
The locking dog 57 is selectively received within an appropriate slot or 
groove 55 formed on one side of a pair of hand grips 54. The dog 57 will 
therefore selectively lock the hand grip in place on the associated weapon 
frame. 
The opposite hand grip may include a laterally extending pin 56 that is 
received within an appropriate opening in the opposite grip for engagement 
by the locking dog 57. This grip is therefore also securely locked to the 
weapon frame when the lock mechanism is shifted to its operative, locked 
orientation. 
Thus, the hand grips are securely locked to the weapon and become 
relatively integrated with the lock 19, further securing the weapon 
against intentional and unintentional use. The hand grips 54 are intended 
to simply replace existing grips without significantly altering the shape 
or "feel" of the grips. The only noticeable difference will be the opening 
for the lock housing and for key access. 
An alternative form of lock body 60 is shown in FIGS. 14-16. Here, the 
alternative lock body includes a coaxial cam block 61 (FIG. 16). The block 
is substantially coaxial with the internal spring 64 and is rotatable to 
selectively lock or unlock the associated plunger 65 in a manner 
substantially similar to that described above. To this end, the plunger 65 
may include an appropriate offset shoulder 66 selectively received within 
a recess 67 formed in the lock block, or, in the locked orientation, the 
shoulder is received and abutted with a lock surface 68. 
Regardless of the configuration or embodiment described above, installation 
of the present safety device is a simple matter. In retrofit situations, 
the firing spring system of the weapon is disassembled and the original 
hammer spring is removed. The hammer spring is then replaced with the 
present safety lock 19. Depending upon the installation, the existing 
hammer pin may be utilized, or a custom hammer pin 34 may be provided with 
the unit to complete the connection between the hammer spring and the 
weapon hammer. Next, a hole is drilled within the adjacent frame or hand 
grip area of the weapon to receive the lock housing 46. In most instances, 
the hole is drilled within the wood, plastic, or other soft material of 
the stock or hand grips. Once again, this is a relatively simple procedure 
and does not involve special tools or training. Upon completion of the 
hole, the weapon can be reassembled and the unit is ready for operation. 
A key (not shown but typically supplied with the lock means 47) may be 
selectively utilized to lock the unit. When locked, the plunger is 
prevented from deflecting along the spring axis and the weapon hammer is 
therefore substantially rigidly connected to the weapon frame and will not 
move back to a cocked position. This therefore eliminates operation of the 
weapon completely as, in the case of a revolver, the cylinder will not 
turn and the trigger will not function. In the case of the lever action 
rifle shown in FIG. 17, the hammer will not move to the cocked position, 
nor can the lever be operated to move the bolt rearwardly to present the 
chamber for access by cartridges. 
Similarly, the semiautomatic weapon 16 shown in FIG. 14 is disabled by the 
locking device 19 to the point where the hammer may not be moved to a 
cocked position, nor may the hammer slide 69 be shifted rearwardly to gain 
access to the barrel chamber. The weapon is therefore completely disabled 
until the key is used to shift the device to the unlocked position. Here, 
the locking surface is pivoted clear of the plunger and the weapon is 
allowed to be used in the normal operating condition. 
If the weapon is stolen, and is in the locked condition, tampering with the 
lock mechanism will not result in a return of the weapon to normal 
operating conditions. If the user is successful in removing the hand grips 
or stock, a procedure which is difficult at best using the arrangement 
shown in FIGS. 10-13, the remainder of the locking mechanism presents 
itself as a formidable obstacle. Removal of the unit from the weapon 
renders the weapon inoperative, as the hammer spring and plunger are 
substantially integrated with the unit and are removed with the remaining 
of the lock mechanism. Thus, there would be no spring remaining to operate 
the hammer. An original spring would have to be supplied to return the 
weapon to the operative condition. Likewise, vandalism of the unit would 
not likely result in the unit returning to an operative position. This is 
true because the spring and plunger are encased within the unit and would 
likely be damaged by any vandalizing of the unit. The spring and plunger 
would therefore, without highly skilled, qualified operation, be rendered 
inoperable by attempted removal of the locking mechanisms. 
In compliance with the statute, the invention has been described in 
language more or less specific as to structural features. It is to be 
understood, however, that the invention is not limited to the specific 
features shown, since the means and construction herein disclosed comprise 
a preferred form of putting the invention into effect. The invention is, 
therefore, claimed in any of its forms or modifications within the proper 
scope of the appended claims appropriately interpreted in accordance with 
the doctrine of equivalents.