Abstract:
The present invention is a quick connect receiver adapter assembly for an automatic or semi-automatic rifle, specifically the AR-15 assault rifle. The adapter system is used to quickly exchange barrels on an AR-15 rifle platform, and allows the user to convert the AR-15 from a single caliber weapon to a multi-caliber weapon. The system has a receiver attached portion comprising a three piece locking ring assembly, and separate barrel adapter assembly which can be attached to any caliber barrel suitable for use with the AR-15 assault rifle.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an improved rifle receiver adapter system for changing barrels of rifles, particularly for an AR-15 based assault rifle. 
       BACKGROUND OF INVENTION 
       [0002]    The AR-15 assault rifle has been in production since 1959, first by ArmaLite, then Colt, and in the preceding years by any number of firearms manufacturers. It was used as the basis for the iconic M-16, and a multitude of other semi-automatic, and automatic rifles. In the intervening years it has become near ubiquitous, and as such the many variants of the basic AR-15 platform come in a variety of sizes, calibers, and barrel lengths. The varieties include not less than 8 different barrel lengths, ranging from 24 inches down to 6.5 inches, and over 65 calibers can be fired using the basic AR-15 platform. In addition to those choices, an AR-15 owner literally has thousands of aftermarket add-ons from which to choose including hand grips, sights, scopes, lasers, lights, and rails for attaching this multitude of accessories. As a result, the AR-15 is perhaps the most versatile and customizable firearm platform on the market today. 
         [0003]    In light of this, the present invention is an adapter which replaces the barrel nut assembly on an AR-15 platform. This adapter allows the user to quickly change barrel systems without special tools. The ability to change barrels is the key to modularity for the AR-15 platform; as the barrel holds the chamber and the chamber determines the caliber. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention is a system for allowing the user to quickly and easily exchange barrels on the AR-15 assault rifle platform. In the present invention there is a Receiver Adapter Assembly, and a Barrel Adapter Assembly. The Receiver Adapter Assembly comprises a three piece unit which includes a threaded locking collar, a partially threaded receiver adapter, and a lock ring; where the lock ring has multiple locking bayonet slots. The Barrel Adapter Assembly comprises a barrel nut replacement with multiple threaded apertures for holding set screws and multiple smooth apertures for individually holding multiple locking lugs. 
         [0005]    In use, an AR-15 is separated into receiver and barrel components, and the barrel is stripped. The Receiver Adapter Assembly is attached to the upper receiver of the rifle by first attaching the locking collar to the barrel end of the receiver, the receiver adapter is threaded on the receiver to secure the locking collar, and the lock ring is threaded onto the lock collar. The Barrel Adapter Assembly is threadably attached to the receiver end of the stripped AR-15 barrel. The Receiver Adapter Assembly and the Barrel Adapter Assembly are aligned and fit together such that the lugs of the Barrel Assembly Adapter are aligned with and inserted into the bayonet slots, and the two assemblies are rotated with respect to one another in order to ensure a mechanical interlock between the upper receiver and the barrel assembly. 
     
    
     
       BRIEF DESCIPTION OF THE DRAWINGS 
         [0006]    The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein: 
           [0007]      FIG. 1  is a view of the invention in use. 
           [0008]      FIG. 2  is a view of the invention separated into receiver and barrel assemblies. 
           [0009]      FIG. 3  is an exploded view of the invention. 
           [0010]      FIG. 4  is an exploded view of the Receiver Adapter Assembly. 
           [0011]      FIGS. 5 a - d    are views of the Locking Collar Assembly and its constituent parts. 
           [0012]      FIGS. 6 a - b    are views of the Receiver Adapter. 
           [0013]      FIGS. 7 a - b    are views of the Lock Ring. 
           [0014]      FIG. 8  is an exploded view of the Barrel Adapter Assembly. 
           [0015]      FIGS. 9 a - b    are views of the Barrel Adapter Assembly and its constituent parts. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Referring to the drawings in general, the present invention will now be described in greater detail. 
         [0017]    The present invention of a Quick Change Rifle Adapter System, denoted by the general reference  10 , and show in use in  FIGS. 1 and 2 , and more fully illustrated in  FIG. 3  is shown. The Quick Change Rifle Adapter System  10  comprises a Receiver Adapter Assembly  12 , and a Barrel Adapter Assembly  14 . The Receiver Adapter Assembly  12  includes a locking collar assembly  16 , a receiver adapter  18 , a lock ring  20 , a locking pin  22 , a spring  24 , and a spring retainer  26 . The Barrel Adapter Assembly  14  includes a barrel adapter  28 , multiple set screws  30 , and multiple locking lugs or dowels  32 . 
         [0018]    The locking collar  16  has a ring shaped body with an outer surface  34 , an inner surface  36 , and top face  38 . The inner surface defines a through hole  40 , and has a ridge or lip  42 , which is perpendicular to the inner surface  36 , and which extends along the entire circumference of the inner surface  36 . The portion of the inner surface  36  which is between the ridge  42  and the top face  38  is milled with threads  44 . The outer surface  34  of the locking collar  16  has  8  rectangular notches  46  which are evenly spaced around the circumference of the outer surface  34 . The outer surface  34  of locking collar  16  also has an aperture  48  located equidistant between two of the notches  46 . Aperture  48  is designed to secure a locking pin  22 , a spring  24 , and a spring retainer  26 . 
         [0019]    Locking pin  22  has a disk shaped head  50  with beveled upper and lower edges, and a perpendicular shaft  52 . The shaft  52  has a solid body of two different diameters along its length with a transition zone in between, such that the upper half  54  has a larger diameter than the lower shaft  56 , and the transition zone  58  comprises a rib having a diameter between that of the upper half  54  and the locking pin head  50 . 
         [0020]    Spring retainer  26  has a hollow cylindrical body with a bore  60  formed therethrough where the diameter of the bore  60  bottom exit is less than the bore  60  at the top entrance. 
         [0021]    The locking pin  22  engages the lock ring  20  to lock and unlock the Barrel Adapter Assembly  14 . 
         [0022]    The receiver adapter  18  has a hollow cylindrical body with an upper surface  62 , a lower surface  64 , and a passage  66  having internal threads  68 . The receiver adapter  18  also has a plurality of equally spaced gas tube clearance holes  70  which extend from the upper surface  62  to the lower surface  64 . In addition, along the lower surface  64  a flange  72  extends perpendicularly to passage  66 . 
         [0023]    The lock ring  20  has a ring shaped body with an upper face  74 , a lower face  76 , an exterior surface  78 , and smooth through hole  80 . The exterior surface  78  of lock ring  20  has threads  82  around its circumference adjacent the lower surface  76  of lock ring  20 . In addition the exterior surface  78  of lock ring  20  also has two distinct types of slots on opposing sides of the lock ring  20 . Bayonet style, or “L”-shaped, lug locking slots  84  are on the upper face  74  side of the lock ring  20 , and straight locking pin slots  86  are on the lower face  76  side of the locking ring. There are 8 lug locking slots  84  spaced equidistantly around the upper perimeter of locking ring  20 . Likewise, the 4 locking pin slots  86  are located 90° from one another along the lower perimeter of locking ring  20 . 
         [0024]    The barrel adapter  28  comprises a unitary body having a cylindrical upper portion  88  with a borehole  90  and an outer surface  92 , and an extended skirt  94 , where the borehole  96  extends through the skirt  94  as well. The skirt  94  also has a flat upper surface  96 , an underside  98 , and a lip  100  which extends from the upper surface  96  of the skirt  94  below the underside  98  of the skirt  94 . The cylindrical upper portion  88  of the barrel adapter  28  has multiple threaded apertures  102  on the outer surface  92  for holding set screws  30  and a ring of multiple scalloped projections  104 , located along the midpoint of the outer surface  92  of the upper portion  88  of the barrel adapter  28 . The lip  100  has multiple apertures or through-holes  106  for holding locking lugs  32 , and a gas tube clearance hole  108 . 
         [0025]    In use, an AR-15 assault rifle is separated into the upper receiver and the barrel assembly portions, and the barrel is stripped. The Receiver Adapter Assembly  12  is assembled by first placing the lock collar  16  on the upper receiver of the rifle with the threaded side facing away from the upper receiver. The receiver adapter  18  is then oriented with the flange  72  of the receiver adapter  18  facing the upper receiver, and the lock ring  20  is oriented with the lower threaded surface  96  facing the upper receiver of the rifle, with the receiver adapter  18  positioned in between the lock ring  16  and the lock collar  20 . The lock collar  20  and the lock ring  16  are then threaded onto the upper receiver of the rifle with the lock ring  16  over the lock collar  20  in a manner that allows the locking collar  20  to spin freely in place. 
         [0026]    The Barrel Adapter Assembly  14  is assembled, by inserting the locking lugs  32  into the smooth apertures on the Barrel Adapter Assembly  14  and threading the set screws  30  into the threaded apertures  102  on the barrel adapter  28 . The stripped barrel is inserted into the upper receiver, such that the barrel alignment pin is fully seated in the corresponding upper receiver alignment slot. The barrel is pushed into the upper receiver until the barrel abuts the face of the upper receiver. The Barrel Adapter Assembly  14  is slid on to the stripped barrel of the rifle with the locking lugs  32  are facing the barrel end, the set screws  30  are facing the muzzle end, and Barrel Adapter Assembly gas tube clearance hole  108  at the Top Dead Center (TDC) location. 
         [0027]    In order to attach the Receiver Adapter Assembly  12  and the Barrel Adapter Assembly  14 , the lock ring  20  is rotated until locking lugs  32  are aligned with the locking lug apertures  110 . The Barrel Adapter Assembly  14  is then slid into the bayonet locking slots  90  of the lock ring  20  and the Barrel Adapter Assembly  14  is inserted into the Receiver Adapter Assembly  12  as far as possible. Light pressure is placed on the locking pin  22 . The lock collar assembly  16  is rotated until the locking pin  22  engages the bayonet locking slots  84  on the lock ring  20 . When the locking pin  22  engages the locking pin slot  86 , the locking pin  22  is fully depressed and the lock collar assembly  16  is rotated until locked. Once locked, release the locking pin  22  and continue rotating the lock collar assembly  16  until it is hand tight. The gas tube  110  is slid through the Barrel Adapter Assembly gas tube clearance hole  108 , a Receiver Adapter Assembly gas tube clearance hole  70 , and the upper receiver gas tube clearance hole (not shown). If properly installed, the gas tube  110  should slide freely through and be aligned Top Dead Center (TDC) with the entire length of the AR barrel  112 . The Barrel Adapter Assembly set screws  30  are tightened and the lock collar assembly  16  is finally tightened by hand or using a tool. 
         [0028]    In order to remove the Quick Change Rifle Adapter System  10 , remove the bolt/carrier assembly and the charging handle. Insert the AR barrel  112  with the Barrel Adapter Assembly  14  you desire to remove into the Receiver Adapter Assembly  12 . Align the Barrel Adapter Assembly locking lugs  32  to the locking lug slots  84  in the lock ring  20 . The Barrel Adapter Assembly is slid into the locking lug slots  84  and the locking pin  22  is lightly pressed to engage the lock ring  20 . While lightly depressing the locking pin  22 , the lock collar assembly  16  is rotated until the lock ring  20  engages the locking lugs  32 . When the lock ring  20  engages, release the locking pin  22  is released and the lock collar assembly  16  is rotated until it is hand tight. The AR barrel  112  is then stripped. After the AR barrel has been stripped, the Barrel Adapter Assembly  14  is loosened and unlocked from the Receiver Adapter Assembly  12 . The set screws  30  are loosened and the Barrel Adapter Assembly  14  is slid off the stripped AR barrel  112 . 
         [0029]    Switching between multiple calibers requires installed Rifle Adapter Assemblies  10  on each barrel and receiver. Once the Rifle Adapter Assembly has been initially installed, the following steps can be followed to switch between barrel assemblies. 
         [0030]    It is important to note that the AR-15 is capable of firing different calibers, and that some calibers require using not only a different barrel, but a different bolt and/or a different magazine. In addition, some calibers may also require different buffers, buffer springs or entire bolt carrier assemblies. 
         [0031]    In order to switch barrel assemblies that utilize the same bolt, initially lock the bolt to the rear of the action. The lock collar  16  is then unscrewed. Once the lock collar  16  begins to loosen, light pressure is placed on the locking pin  22  while continuing to loosen the Lock collar  16 . When the locking pin  22  engages the lock ring pin slot  90 , fully depress the locking pin  22  and continue rotating in the same direction to unlock the Quick Change Rifle Adapter System  10 . The locking and unlocking requires less than a ¼″ of movement in either direction once the locking pin  22  is engaged. 
         [0032]    The entire barrel assembly is removed from the AR upper receiver by pulling it away from the AR receiver. The new barrel assembly is installed by lining the gas tube Top Dead Center (TDC) to the Top Dead Center (TDC) Receiver Adapter gas tube clearance hole  70  and inserting the barrel extension into the receiver. The Barrel Adapter Assembly locking lugs  32  are aligned with the locking slots  88  on the lock, ring  20 . The barrel is then fully seated into the AR receiver. The lock collar  16  is tightened while placing light pressure on the locking pin  22 . When the locking pin  22  engages the lock ring locking pin slot  86 , fully depress the locking pin  22  and continue rotating in the same direction to lock the Quick Change Rifle Adapter System  10 . The locking and unlocking requires less than a ¼″ of movement in either direction once the locking pin  22  is engaged. Release the locking pin  22  and continue to tighten the lock collar  16  until it will not tighten any more. 
         [0033]    In order to switch barrel assemblies that require different bolts, initially, lock the bolt to the rear of the action. The lock collar  16  is turned to unscrew the Quick Change Rifle Adapter System  10 . Once the lock collar  16  begins to loosen, place light pressure on the locking pin  22  while continuing to loosen the lock collar  16 . When the locking pin  22  engages the lock ring  20  locking pin slot  86 , the locking pin  22  is fully depressed and the lock ring  20  rotated in the same direction to unlock the Quick Change Rifle Adapter System  10 . The locking and unlocking requires less than a ¼″ of movement in either direction once the locking pin  22  is engaged. The entire AR barrel assembly is removed from the AR receiver by pulling it away from the AR receiver. After removing the AR barrel assembly, separate the AR upper and lower receivers. This can be done by pulling one or both receiver takedown pins. 
         [0034]    The bolt carrier assembly is removed and the bolt is changed. With the new bolt in the upper receiver, the AR upper and lower receiver are reassembled. The new barrel assembly is installed by lining the gas tube  110  Top Dead Center (TDC) to the TDC Receiver Adapter gas tube clearance hole  70  and inserting the barrel extension into the receiver. Align the Barrel Adapter Assembly locking lugs  32  with the locking lug slots  84  on the lock ring  20 . The&#39;barrel assembly is fully seated into the AR receiver. The lock collar  16  is tightened while light pressure is placed on the locking pin  22 . When the locking pin  22  engages the lock ring locking pin slot  86 , the locking pin  22  is fully depressed and the locking collar  16  is rotated in the same direction to lock the Quick Change Rifle Adapter System  10 . The locking and unlocking requires less than a ¼″ of movement in either direction once the locking pin  22  is engaged. The locking pin  22  is released and the lock collar  16  is tightened. 
         [0035]    With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function, and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention. 
         [0036]    Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.