Shim supported upon a pivot pin between upper and lower receivers of an ar-15/m16/m4 style firearm and for reducing misalignment and play

Abstract

An improved shim construction incorporating a thin body exhibiting a profile generally matching a selected mounting ear of a lower assembleable receiver, the shim including an arcuate perimeter with an flat interconnected base surface. The body exhibits an aperture defined therein such that, upon placement between an inner facing surface of the ear and an intermediate positioned cylindrical shaped portion, a subsequent widthwise traversing installation of a pivot pin causes the shim body to be sandwiched between the receivers to occupys an excess tolerance, thereby reducing or eliminating instances of misaligning slop or play exhibited between the receivers. The shim may exhibit a thickness in a range of 0.001″ to 0.010″. A plurality of shims can be provided as a kit and which are applied in scalable fashion to compensate for varying excess tolerance established between the receivers.

1 . A shim insertable between a mounting location established between upper and lower assembleable receivers of a firearm, a first of the receivers exhibiting a pair of spaced apart ears, each of said ears exhibiting an arcuate profile with a level base surface, a pair of widthwise aligning apertures extending through said ears, the other of the receivers exhibiting a generally cylindrical shaped projection aligning between said spaced apart ears, a widthwise extending aperture defined through said cylindrical shaped portion and which communicates with said aligning apertures in said ears; said shim stock comprising:
 a thin body exhibiting a profile generally matching a selected ear and including an arcuate perimeter with an flat interconnected base surface; and   said body exhibiting an aperture defined therein such that, upon placement between an inner facing surface of a selected ear and the intermediate positioned cylindrical shaped portion and subsequent widthwise traversing installation of a pivot pin, said body being sandwiched between said receivers and occupying an excess tolerance thereby reducing or eliminating instances of misaligning slop or play exhibited between the receivers.   
     
     
         2 . The shim as described in  claim 1 , said shim exhibiting a thickness in a range of 001″ to 0.010″. 
     
     
         3 . The shim as described in  claim 1 , further comprising a plurality of shims provided as a kit and which are applied in scalable fashion to compensate for varying excess tolerance established between the receivers. 
     
     
         4 . The shim as described in  claim 3 , at least first and second of said shims exhibiting identical cross sectional outlines combined with varying thicknesses ranging between 0.001″ to 0.010″. 
     
     
         5 . A shim kit adapted to being insertable between a mounting location established between upper and lower assembleable receivers of a firearm, comprising:
 the lower receiver exhibiting a pair of spaced apart ears, each of which exhibiting an arcuate profile with a level base surface, a pair of widthwise aligning apertures extending through the ears;   the upper receiver exhibiting a generally cylindrical shaped projection aligning between said spaced apart ears, a widthwise extending aperture defined through said cylindrical shaped portion and communicating with the aligning apertures in the ears;   said shim kit including a plurality of bodies, each exhibiting a profile generally matching a selected ear and including an arcuate perimeter with an flat interconnected base surface; and   each of said bodies exhibiting an aperture defined therein such that, upon placement in successively stacked fashion between an inner facing surface of a selected ear and the intermediate positioned cylindrical shaped portion, and subsequent widthwise traversing installation of a pivot pin, said bodies being sandwiched between said receivers and occupying an excess tolerance thereby reducing or eliminating instances of misaligning slop or play exhibited between the receivers.   
     
     
         6 . The shim kit as described in  claim 5 , at least first and second of said shims exhibiting identical cross sectional outlines combined with varying thicknesses. 
     
     
         7 . The shim as described in  claim 6 , said shims exhibiting a thickness in a range of 001″ to 0.010″.