초록 ▼

A system that converts an original equipment (OEM) AR-15 rifle to a rifle capable of firing cartridges of at least two different calibers. Two or more barrel liners are provided for cartridges of differing calibers. Each liner is insertable through a rear opening of an upper receiver portion of the

A system that converts an original equipment (OEM) AR-15 rifle to a rifle capable of firing cartridges of at least two different calibers. Two or more barrel liners are provided for cartridges of differing calibers. Each liner is insertable through a rear opening of an upper receiver portion of the rifle and into a smooth bore barrel of a modified barrel assembly. Each liner comprises a tube portion having a longitudinal bore and a head portion with an opening that communicates with said bore. An adapter bolt carrier assembly is substituted for the OEM AR-15 bolt carrier assembly. The substituted assembly includes a bolt that carries the firing pin and is slidably mounted on a rail guide. A front end of the rail guide has a tongue extension with a slot that receives a pin attached to a rear end of a liner head. A support rail is fixed to a rear end of the rail guide. A spring extends from the support rail to the bolt, thereby pressing the bolt against the liner head. A magazine insert, insertable into an OEM ammunition magazine, accepts cartridges of differing calibers.

대표청구항 ▼

I claim: 1. A caliber convertible, upper receiver system for a magazine-equipped, manually operated or semiautomatic or fully automatic firearm, said upper receiver system being adapted to replace the original equipment upper receiver portion and to attach to the original equipment lower receiver p

I claim: 1. A caliber convertible, upper receiver system for a magazine-equipped, manually operated or semiautomatic or fully automatic firearm, said upper receiver system being adapted to replace the original equipment upper receiver portion and to attach to the original equipment lower receiver portion of said firearm in order to render the firearm capable of firing either a first cartridge or a second cartridge, the first and second cartridges having dissimilar calibers, the system comprising: an upper receiver assembly attachable to the lower receiver portion of the firearm, said assembly including a charging handle; and an upper receiver extending longitudinally from a rear end to a front end and having a longitudinally-extended, upper channel portion into which the charging handle is insertable through a rear opening thereof and a pair of side walls coextensive with the channel portion and depending therefrom that define a substantially cylindrical interior space, open at the bottom, and an externally threaded, cylindrical extension at a front end of the upper receiver that is coaxial with said interior space; a barrel assembly extending longitudinally from a rear, firing chamber end to an opposite, front end, said barrel assembly including a barrel having a straight, cylindrical bore; and means to attach said rear end to the upper receiver assembly, adjacent to and aligned with the firing chamber; a first barrel liner dimensioned for insertion into the barrel bore and to receive at a rear, firing chamber end thereof a bullet fired from the first cartridge in the firing chamber, and to conduct the bullet through the barrel assembly and out an opposite, front end of said barrel liner, said first barrel liner including a first barrel liner head at the rear end of said liner, said head having a longitudinally-directed aperture for receiving a bullet fired from the firing chamber, and a first liner tube that extends longitudinally from said head to the front end of the first liner, said tube having a bore aligned with the aperture of said head; a second barrel liner dimensioned for insertion into the barrel bore and to receive at a rear, firing chamber end thereof a bullet fired from the second cartridge in the firing chamber, and to conduct the bullet through the barrel assembly and out an opposite, front end of said barrel liner, said second barrel liner including a second barrel liner head at the rear end of said liner, said head having a longitudinally-directed aperture for receiving a bullet fired from the firing chamber, and a second liner tube that extends longitudinally from said head to the second end of the second liner, said tube having a bore aligned with the aperture of said head; a bolt adapter carrier assembly insertable into the cylindrical interior space of the lower receiver, said assembly including a bolt that carries a spring-loaded firing pin mounted for reciprocal, longitudinal movement within a firing pin bore of the bolt, and means for attaching and disattaching alternately the head of either the first or the second barrel liner to said carrier assembly; and a magazine adapter insert dimensioned for insertion and retention within the magazine of the firearm and adapted to receive and store a plurality of the first or second cartridges for use as ammunition by the firearm. 2. The system of claim 1, wherein the head of each of the liners includes a pair of spaced-apart legs, a liner engagement pin mounted between the legs on a first side of the head aperture, and a first slot disposed normal to the pin on an opposite side of the head aperture; and the means for attaching and disattaching the head from the bolt adapter carrier assembly includes a rail guide that extends longitudinally from a rear end to an opposite, front end, said front end having a tongue extension with a second slot for receiving the liner engagement pin, and said tongue extension being cut out on one side to receive one of the legs of a liner head and to permit the other leg to be placed adjacent to the tongue extension in side by side relation so that the legs straddle the tongue extension; a support rail fixedly mounted to the rear end of the guide rail and extending part way toward the front end of the support rail; wherein said bolt is slidably mounted on the guide rail for movement between the support rail and the front end of the guide rail, and spring means for urging the bolt away from the support rail and into engagement with the head of a liner. 3. The system of claim 2, wherein the spring means includes an apertured, rear lug mounted to the support rail; an apertured, front lug mounted to the bolt; a spring support pin disposed parallel to the guide rail and having a rear end inserted into the apertured first lug and an opposite, front end inserted into the apertured, second lug; and a coil spring mounted on the spring support pin between the first lug and the second lug. 4. The system of claim 3, wherein an exterior surface portion of the bolt is recessed to form a thumb depression in order to facilitate manual retraction of the bolt while attaching the head of a barrel liner to, or disengaging the head of a barrel liner from, the bolt adapter carrier assembly. 5. The system of claim 4, wherein the barrel assembly further comprises a front sight mounted on a forward portion of the barrel, upper and lower hand guards mounted on an exterior surface of the barrel, and a barrel extension that is coaxial with the barrel and extends from the barrel into the threaded cylindrical extension of the upper receiver. 6. The system of claim 5, wherein the first cartridge is a .22 caliber, rim-fire cartridge and the second cartridge is a .17 caliber, rim-fire cartridge. 7. The system of claim 6, wherein the term "firearm" refers to an AR-15. 8. The system as in any one of claims 1-7, wherein the magazine adapter insert includes a front wall and a rear wall joined by left and right side walls and a bottom wall, thereby defining a closed space that is open at a top end thereof; a spring-loaded follower disposed within said closed space, an upper portion of said follower being retractable into said closed space against the urging of a follower spring when a cartridge is manually pressed down against an upper end of the follower; and a cartridge keep including left and right walls attached to an upper end of the left and right walls of the insert, respectively, which left and right walls extend outward as front and rear extensions of said cartridge keep left and right walls, and front and rear top walls that join said front and rear extensions, and a pair of cartridge retainer tabs that extend upward from the left and right walls of the keep; wherein the insert is dimensioned for insertion into an open, upper end of an ammunition magazine by pressing the bottom wall of the insert up against the follower of the magazine as far as it will go and locking the keep into a fixed position within inwardly-directed tab extensions that extend from an upper end of a standard, original equipment ammunition magazine. 9. For use in a caliber convertible, magazine-equipped, manually operated or semiautomatic or fully automatic firearm capable of firing either a first cartridge or a second cartridge through a barrel bore of the firearm, the first and second cartridges having dissimilar calibers, and the firearm including an upper receiver portion and a lower receiver portion, the combination of a bolt adapter carrier assembly and first and second barrel liners, comprising: a first barrel liner dimensioned for insertion into the barrel bore and to receive at a rear, firing chamber end thereof a bullet fired from the first cartridge in the firing chamber, and to conduct the bullet through the barrel assembly and out an opposite, front end of said barrel liner, said first barrel liner including a first barrel liner head at the rear end of said liner, said head having a longitudinally-directed aperture for receiving a bullet fired from the firing chamber, and a first liner tube that extends longitudinally from said head to the front end of the first liner, said tube having a bore aligned with the aperture of said head; a second barrel liner dimensioned for insertion into the barrel bore and to receive at a rear, firing chamber end thereof a bullet fired from the second cartridge in the firing chamber, and to conduct the bullet through the barrel assembly and out an opposite, front end of said barrel liner, said second barrel liner including a second barrel liner head at the rear end of said liner, said head having a longitudinally-directed aperture for receiving a bullet fired from the firing chamber, and a second liner tube that extends longitudinally from said head to the front end of the second liner, said tube having a bore aligned with the aperture of said head; and a bolt adapter carrier assembly for insertion into the interior space of the lower receiver, said assembly including means for attaching and disattaching alternately the head of either the first or the second barrel liner to said carrier assembly. 10. The combination of claim 9, wherein the head of each of the liners includes a pair of spaced-apart legs, a liner engagement pin mounted between the legs on a first side of the head aperture, and a first slot disposed normal to the pin on an opposite side of the head aperture; and the means for attaching and disattaching the head from the bolt adapter carrier assembly includes a rail guide that extends longitudinally from a first end to an opposite, second end, said second end having a tongue extension with a second slot for receiving the liner engagement pin, and said tongue extension being cut out on one side to receive one of the legs of a liner head and to permit the other leg to be placed adjacent to the tongue extension in side by side relation so that the legs straddle the tongue extension; a support rail fixedly mounted to the rear end of the guide rail and extending part way toward the front end of the support rail; a bolt slidably mounted on the guide rail for movement between the support rail and the front end of the guide rail, said bolt having a longitudinally-extended firing pin bore: and spring means for urging the bolt away from the support rail and into engagement with the head of a liner. 11. The combination of claim 10, wherein the spring means includes an apertured, rear lug mounted to the support rail; an apertured, front lug mounted to the bolt; a spring support pin disposed parallel to the guide rail and having a first end inserted into the apertured first lug and an opposite, second end inserted into the apertured, second lug; and a coil spring mounted on the spring support pin between the first lug and the second lug. 12. The combination of claim 11, wherein an exterior surface portion of the bolt is recessed to form a thumb depression in order to facilitate manual retraction of the bolt while attaching the head of a barrel liner to, or disengaging the head of a barrel liner from, the bolt adapter carrier assembly. 13. The combination of claim 12, wherein the first cartridge is a .22 caliber, rim-fire cartridge and the second cartridge is a .17 caliber, rim-fire cartridge. 14. The combination of claim 13, wherein the term "firearm" refers to an AR-15.