Abstract:
A disconnector for a rifle wherein the disconnector is formed with a hook-under portion which is provided with a sharp trigger body contact ridge which contacts on a center line (rifle longitudinal axis) of the underside of a portion of the trigger body when the disconnector is in a neutral position during the first stage of a two stage trigger pull.

Description:
This application is a Continuation-In-Part of application Ser. No. 12/228,103 filed Aug. 11, 2008 now abandoned and claims the benefit of the Provisional Patent Application Ser. No. 60/964,021 filed Aug. 9, 2007. 
    
    
     BACKGROUND 
     1. Field 
     The technical field of the present invention resides in a unique trigger disconnector structure and its manufacture for firearms and in particular for the AR15-T400 rifle. 
     2. Prior Art 
     The current various trigger assemblies on the market such as described in U.S. Pat. Nos. 5,881,485; 6,131,324; 5,501,134; 4,937,964; and 4,937,964 the disclosures of which are hereby incorporated herein by reference in their entireties, do not incorporate a center line trigger pull which allows the disconnector to hook under the trigger body and bear on a lateral, centered pivot line on the trigger body. The present structure allows for more accurate machining of the disconnector and a cleaner, lighter and crisper trigger pull in that it allows the shooter to feel the first and second stages of the trigger pull without any drag or roughness. 
     SUMMARY 
     The present disconnector works from the bottom of the trigger body with a hook under portion laterally centered with the trigger body and with a substantially line pivot fulcrum contacting the trigger body. This design allows the disconnector to work freely on the very accurately ground trigger body surface giving a center line trigger pull with less torquing of the trigger pivot giving much less drag and imbalance to the firing process. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention will be understood further from the drawings herein and their description, wherein: 
         FIG. 1  is a side view with portions broken away for clarity, of a rifle having the present disconnector structure; 
         FIGS. 2 ,  2 A and  2 B are side views of the prior art (U.S. Pat. No. 5,501,134) trigger-disconnector-safety assembly as shown in  FIGS. 9 ,  10  and  11  respectively of that patent; 
         FIG. 3  is an enlarged side view of the trigger-disconnector assembly of  FIG. 1  with portions broken away for clarity; 
         FIG. 3A  is a bottom up view of the trigger body portion lying adjacent to ridge  18  of the disconnector; 
         FIG. 4  is a top view taken along line  4 - 4  in  FIG. 3 ; 
         FIG. 5  is a cross-sectional view of the disconnector and adjacent trigger body portion taken along line  5 - 5  in  FIG. 3 ; 
         FIG. 6  is a side view of the disconnector and portions of the adjacent trigger body taken along line  6 - 6  in  FIG. 5 ; 
         FIG. 6A  shows a variation in shape of the hook under portion of the present disconnector while retaining the ridge  18  structure; 
         FIG. 6B  is a bottom up view taken along line  6 B- 6 B in  FIG. 5 ; 
         FIG. 6C  is a side view taken along line  6 C- 6 C in  FIG. 5 ; 
         FIG. 7  is a top view of the isolated disconnector taken along line  7 - 7  in  FIG. 5 ; 
         FIG. 8  is a dimensioned (in inches) detail of the disconnector pivot pin; and 
         FIG. 9  is a dimensioned (in inches) detail of the disconnector engagement compression spring. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , an AR15 rifle is shown with side wall portions of the breech  12  housing broken away and showing (within the dotted line) the present trigger-disconnector-safety assembly  13  with certain parts thereof numbered as in the aforesaid FIGS. 9, 10 and 11 of said U.S. Pat. No. 5,501,134. 
     The present disconnector is a unique improvement over the structures of the prior art as shown for example in present  FIGS. 2 ,  2 A and  2 B, and the function and need for a disconnector is described in detail in U.S. Pat. No. 5,501,134 at Col. 2, lines 11 thru 67, Col. 3, lines 1 thru 33, Col. 5, lines 7-67, and Col. 6 lines 1-55. Concisely stated, disconnectors allow an experienced shooter to feel a two stage pull of the trigger wherein in the first stage of the finger pull the shooter can readily feel the trigger move but then stop against a disconnector spring resistance, but in the second stage of the finger pull the shooter in overcoming the spring resistance, can barely—if at all—feel motion of the trigger until firing occurs. Greatly improved shooting accuracy is thus achieved. 
     Referring to  FIGS. 3-9  the present disconnector  14  in a most preferred embodiment comprises a cam portion  16  and a hook under portion  17  which is machined to provide a short lateral ridge  18  which terminates in an upper contact surface  19  which preferably is substantially a line surface of from about 0.0001″ to about 0.005″ in width  23  and from about 0.005″ to about 3/16″ in length  24 , most preferably from about 0.01″ to about ⅛″ in length. 
     Disconnector  14  is pivotally mounted on trigger body  35  by pin  54  and compression spring  37  has one end mounted in pocket  49  in the disconnector and the other end bearing against trigger body  35 . As more clearly seen in  FIGS. 3A and 6 , trigger body  35  preferably but not necessarily is formed with a raised slave portion  50  which can be readily machined ground to precisely adjust the neutral position of cam portion  16  without trying to dimension the whole under cut surface  51  of the trigger body  35 . 
     In a preferred embodiment the invention comprises a firearm trigger assembly having a receiver housing  15 A, a firing pin hammer  30  pivotally mounted in the housing and having a hook  31  formed with a trigger engagement surface  32 , a trigger  20  having a body  35  pivotally mounted in the housing and having a hook  21  formed with a hammer engagement surface  22  and having an under cut surface  51 , a disconnector  14  pivotally mounted on the trigger body  35  and having an upper cam portion  16 , a lower hook-under portion  17  and an intermediate connector portion  56  forming a trigger body receiving gap  52 , the disconnector having a center line  57  substantially aligned with a longitudinal axis of the firearm, the hook-under portion  17  being formed with a laterally extending ridge  18  on its upper surface, the ridge having an upper contact surface  19  of a width of from about 0.0001″ to about 0.05″ and a length of from about 0.01″ to about ⅛″, and spring means urging the disconnector in a pivotal motion to move cam portion  16  toward said hook  21  and to engage upper contact surface  19  with the under surface  51  of the trigger body  35 , wherein at least a portion of the contact surface  19  is positioned on the center line. 
     In manufacturing the present Hook0Under Trigger Assembly two investment castings are used. The castings material is 8620 steel and the heat treatment required is a case hardened  50 - 55  with a core depth of 0.010″-0.015″. Referring to  FIG. 3 , this view shows the trigger with a large pin hole  46  machined to 0.156″ and a disconnector pin hole  53  drilled and reamed to 0.094″. The under cut surface  51  on the bottom of the trigger is 0.110″ from the bottom of the disconnector slot.  FIG. 4  shows the 0.155″ spring pocket  49  in the disconnector to the depth of 0.275″ and the 0.094″ pin  54  braded in place. The disconnector working surface (slave portion, if used)  50  on the bottom of the trigger body  35  is ground to 0.110″+0.001″-0.001″. The angle on the disconnector hook is a clean square ground surface with a tolerance of 0.001″. 
     Assembly Procedure 
     The present Trigger Assembly is placed in the AR15 receiver by breaking open the receiver by pressing the lower receiver locking pin and swinging the barrel assembly up. Then remove both the hammer and the trigger pins from the side of the receiver. Remove hammer and trigger from the receiver. The AR15-T400 comes completely assembled. Replace the old hammer and trigger with the AR15-T400 set by dropping the trigger in place and inserting the trigger pin. Then place the hammer in the receiver and insert the hammer pin. Lower barrel assembly and lock in place with lower receiver locking pins. The AR15-T400 will now function. 
     The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications will be effected within the spirit and scope of the invention.