the breech lock mechanism 10 illustrated in the accompanying figures is inserted as a self - contained unit into the pistol grip 61 of a grip 60 of the pistol . movably mounted on the grip 60 is a breech mechanism 11 in which the barrel is mounted . a firing pin 12 is capable of moving inside the breech mechanism 11 , and is biased by a force applied by a spring in its rear base position illustrated in fig1 and 5 , in which it projects beyond a rear end surface 9 of the breech mechanism 11 . the breech lock unit 10 has a housing 13 . in the housing 13 , a stroke hammer 14 is mounted so that it can pivot around a first shaft 15 . a drive lever 16 can pivot on the same shaft 15 . the pivoting motion of the lever 16 with respect to the hammer 14 is restricted by two stop surfaces 17 , 18 of the hammer 14 in the two directions of rotation . the strike hammer 14 is biased by a spring 19 with respect to the lever 16 toward the rear against the first stop or stop surface 17 . a percussion rod 22 is connected to the lever 16 , at some distance from the shaft 15 . the rod 22 is guided in a boring 23 of a transverse web 24 of the housing 13 . between a disc 25 secured on the end of the rod by a transverse pin and the web 24 , the prestressed striker spring 26 is inserted , which applies tension to the rod 22 . in the base position illustrated in fig1 to 3 , a second stop or stop surface 27 of the rod 22 is in contact against the web 24 . the strike surface 28 of the hammer 14 in this base position is at an angle of approximately 150 with respect to the rear end surface 9 of the breech mechanism 11 so that , if the breech mechanism 11 is pushed backward by an impact , the hammer 14 cannot strike the firing pin 12 . the hammer 14 is engaged with a first catch 31 in a spring - loaded pawl 29 . the lever 16 has some play with respect to the contact surface 17 . the hammer 14 interacts in a known manner with a trigger rail 32 . in the housing 13 , a slide 33 is mounted so that it can be displaced , and presses the rail 32 by means of a spring 34 in engagement into a catch 35 of the hammer 14 . an uncocking lever 36 is also rotationally mounted on a second shaft 44 . by means of the uncocking lever 36 , the hammer 14 can be pivoted back out of the cocked position illustrated in fig5 into the base position illustrated in fig1 to 3 . also fastened to the housing 13 is an ejector mechanism 37 which , after the shot has been fired , ejects the empty cartridge through an opening in the breech mechanism 11 . the breech lock unit 10 functions as follows : when the trigger is pulled , the rail 32 is pulled forward . it pivots a safety lever 42 ( fig6 ), which can also pivot around the shaft 15 and presses a safety slide 43 out of a locking catch 45 of the firing pin 12 , on which a downward load is exerted by a spring 46 . the lever 42 presses the pawl 29 forward out of its engagement with the catches 31 , 38 . the rail 32 , by means of its engagement in the recess or catch 35 , drives the hammer 14 against the force of the spring 26 into the cocked position illustrated in fig5 . the rail 32 runs along a control cam 47 ( fig6 ), which displaces it against the force of the spring 34 downward and out of engagement with the catch 35 . the hammer 14 is released , so that the spring 26 , by means of the impact rod 22 acting as a connecting rod , the lever 26 and the stop surface 17 , accelerates the hammer 14 against the breech mechanism 11 , until the surface 27 comes into contact against the web 24 . as a result of the mass inertia of the hammer 14 , said hammer 14 continues to rotate , strikes the firing pin 12 and initiates the firing process . after the shot has been fired , the breech mechanism 11 slides back and the empty cartridge shell is ejected . the process described above is conventionally called “ double action ” ( da ). when , after the shot has been fired or as a result of manual action , the breech mechanism slides backward , a control cam of the breech mechanism pivots the trigger rail 32 downward and the hammer 14 backward , so that the hammer is engaged with the second catch 38 on the pawl 29 . when the trigger is released , the rail 32 slides backward into engagement with the lever 42 which , the next time the trigger is actuated , pushes the pawl 29 out of the catch 38 after it moves past the da firing position ( single action ). fig7 to 9 illustrate the function of the uncocking lever 36 . fig7 shows the uncocking lever 36 in the base position and the strike hammer 14 in its safety position as illustrated in fig1 to 3 , in which the pawl 29 is engaged in the safety catch 31 . the uncocking lever 36 has an arm 48 with a second means , e . g . a projecting lug 49 , which interacts with a slide surface of the strike hammer 14 . a first means , e . g . a trigger tab 51 , projects forward from the arm 48 . when the grip 52 of the uncocking lever 36 is depressed , the trigger tab presses against a web 53 of the pawl 29 . when the hammer 14 with its single - action catch 38 is engaged in the pawl 29 , the pawl 29 is thereby pivoted out of engagement with this catch 38 . fig8 shows this process immediately before the release of the hammer 14 . as the uncocking lever 36 pivots further , the hammer 14 is released , so that the slide surface 50 impacts the lug 49 ( fig9 ). as the uncocking lever 36 pivots back , the hammer 14 is gently returned by the sliding of the lug 49 on the surface 50 and simultaneously the pawl 29 is released once again , so that it engages in the catch 31 ( fig7 ). fig1 illustrates the installation of the breech lock unit 10 into the grip piece 60 of the pistol . the grip piece 60 , in the pistol grip 61 , has a magazine shaft 62 that runs at an angle to the axis for the insertion of a magazine , which is closed at the back by a rear wall 63 . the two side walls 64 that continue beyond the wall 63 have grooves 65 with a rectangular cross section that run parallel to the wall 63 . the breech lock unit 10 , on the forward edge on both sides , has two molded rails 66 that project laterally and fit into the grooves 65 . the breech mechanism 11 is guided in two additional rails 67 on the upper edge of the housing 13 . the breech lock unit 10 is inserted from above into the grip piece 60 and is secured by two cross - bolts 68 , 69 which are inserted through transverse borings 70 to 72 in the two side walls 64 and in the housing 13 , or recesses 73 in the housing 13 . fig1 also shows the trigger tab 74 , which is pivotably mounted in a front insert ( not shown ). the front insert also has lateral rails that correspond to the rails 67 to guide the breech mechanism 11 . the trigger rail 32 is pivotably connected to the trigger tab 74 . because the striker rod 22 transmits the spring force by tension , and the point of application of force of the striker rod 22 with respect to the hammer 14 is therefore in front of the shaft 15 , the breech lock unit described above is slimmer than is possible with the pressure transmission mechanisms of the prior art , and optimal drive conditions are achieved , because the striker rod 22 in the pistol grip must be installed inclined downward and toward the rear . by integration of the slide 33 into the trigger rail 32 of the uncocking lever 36 , of the safety lever 42 and of the ejector mechanism 37 , a plurality of functions can be combined in one compact unit , which simplifies manufacture . because the hammer 14 in the base position is locked in the safety catch 31 and the striker rod 22 is stopped against the stop 24 , there is multiple protection against an unintentional discharge . a first safety measure is the above referenced protection provided by the inclination of the striking surface 28 . a second safety measure is the securing of the firing pin by the safety slide 43 . a third safety measure is provided by the uncocking lever 36 . if the person using the pistol uncocks the strike hammer by holding it back , actuating the trigger and then slowly returning the hammer 14 , after the trigger has been released , the hammer 14 is automatically returned to the safety catch 31 . because the breech lock unit 10 is inserted into the grip piece 60 as a pre - assembled unit , it can easily be replaced by another breech lock unit 10 , for example so that the original can be repaired . it is also possible to prepare a plurality of different breech lock units 10 , e . g . in addition to the unit described above , a unit can be used that does not have the catch 38 , so that the pistol is a double - action - only pistol . breech lock units with different impact forces can also be made available for different types of ammunition . the breech lock unit described above therefore also makes it possible to adapt the pistol to meet different requirements .