1. Field of Invention
This invention relates generally to a device for aligning the sights on firearms utilizing the boresighting technique. More specifically, it relates to a bore adapter and laser sight mounting assembly which can utilize one of several commercially available laser light beam sighting devices.
2. Description of Prior Art
Before a firearm can be fired with any accuracy, the sights must be aligned with the central axis of the bore of the weapon. This process is commonly referred to as boresighting. Weapons that can be "broken down" so that the full extent of the bore is visible, are sighted by looking down the bore at a point some distance from the weapon, usually a target. Then the sights on the weapon are adjusted so they roughly correspond to the same point on the target. Finally, the weapon is fired several times, and fine adjustments are made. Weapons which can't be broken down are simply anchored then fired and adjusted until the sights are reasonably close to the spot where the bullet impacts the target. This is a laborious and expensive process. With optical scopes, infrared or laser sights, the process must be repeated each time the firearm receives a jolt or the sighting devices are moved or replaced.
Several types of devices have been developed which attempt to facilitate this process. One type includes an internal laser light emitter. It fits into the firearm chamber and directs a beam of light through firearm bore and onto a target. The scope may be aligned with the target using either visual sighting or a second fight emitting device mounted on the scope. An example of this system is illustrated in U.S. Pat. No. 3,782,832 entitled METHOD OF BORESIGHT ALIGNMENT OF A WEAPON, issued Jan. 1, 1974 to Hacskaylo. However, as with the previously described device, slight misalignment of the housing within the chamber will cause relatively large errors in the alignment of the bore with the target. Also, a laser fight emitter must be custom built for each caliber or firearm, making this device expensive for the average gun owner or military unit in the field who may possess firearms of several different caliber.
U.S. Pat. No. 5,001,836, issued Mar. 26, 1991 to Cameron et al, entitled APPARATUS FOR BORESIGHTING A FIREARM also includes a cartridge which fits into the chamber of a firearm. However, the light emitting device is external to the cartridge and light is fed to the cartridge via a fiber optic element. The device also includes a system of lenses and another light emitting source external to the firearm contained in a box or the like. Similar to U.S. Pat. No. 5,060,391 also issued Oct. 29, 1991 to Cameron et al. These apparatuses would be expensive and unwieldy to carry into the field, since they could be easily damaged if dropped. Also these devices are only designed for aligning optical sights.
U.S. Pat. No. 4,136,956 issued Jan. 30, 1979 to Eichweber, entitled INTEGRATED ATTACHING AND ALIGNING APPARATUS FOR LASER DEVICES IN GUN BARRELS utilizes a custom-designed laser light which fits into a tubular unit which is inserted into the muzzle of a firearm. The tubular unit is retained in the barrel by resilient material rings which will deteriorate over time due to contact with residual solvents and oils present in the barrel. This will cause the device to become misaligned. It also requires a custom-built laser light emitter, making the device expensive.