or nail into a work surface a forward end 59 of the power spring 57 is also received in the plunger the return spring 90 holds the handle lever 22 against a handle stop 18 in this position generally as the handle 22 is pivoted downwardly it causes the trigger lever 31 to pivot clockwise as shown in this figure as this occurs the trigger portion 57 lifts the plunger 54 through the plunger ledge 56 and against the force of the power spring 57 the trigger portion 57 continues to lift the plunger 54 to a point at which the plunger 54 becomes disengaged from the trigger portion as shown in fig2 as the handle 22 begins to be pivoted about point 24 and counterclockwise as shown in this figure the connection of lever 22 to pin 26 also drives the links 28 and 34 in a similar direction as this movement occurs the roller 30 moves within the slot 32 however with such movement the link 34 begins to constrain the roller 30 to move downwardly and to the right as shown in this figure which increases the distance between pivot 40 and roller 30 see fig5 b and 5c when this occurs the firing lever 31 also begins to pivot about its pivot point 40 downwardly with the roller 30 as this occurs and as can be seen in the left side of fig2 the trigger point 57 begins to lift the plunger ledge 56 lifting the plunger 54 as is clear from this figure the spring 57 begins to flex and urge the plunger in.