Installation instructions for the M2hb Crankfire Systems unit:

1. Remove the back plate from the receiver.

2. The original butterfly trigger and spacer will need to be removed from the back plate and replaced with the new trigger and spacer provided.  The trigger is retained in the back plate by a 3/16" diameter cross pin that can be pushed out from either side of the back plate.  You will need to apply some upward pressure on the trigger against the return spring to allow the pin to slide easily and to prevent the trigger return spring from taking flight when the pin is removed.  Once the pin is clear of the trigger let the spring extend slowly and then remove it.  You will reuse this spring and pin with the new trigger. The original butterfly trigger and spacer can be withdrawn to the rear of the back plate at this point.  I have found the easiest method of getting the pin/trigger/spring/spacer all gathered up and in place; is to use a pin punch inserted from one side to get the pieces roughly in line.  Then "Chase" the punch back out with the trigger pin as it is installed.

3. Installation of the new trigger and spacer is essentially the reverse of the above, however the new trigger can be inserted from either the front or rear of the back plate.

4. Remove the two 8-32 button head screws on the top of the Crankfire unit and remove the dust cover.

5. Remove the two 1/4-28 socket head cap screws from the mounting clamp and remove the clamp cap.

6. Position the Crankfire unit onto the back plate by turning it at a slight angle to get the single shot trigger past the R.H. spade handle and making sure that the rocker arm is above the projecting portion of the new back plate trigger.  Seat the buffer tube in the main housing clamp.

7. At this point it is easier to proceed if the back plate and unit are positioned upside down on the table.

8. Re install the clamp cap and the two 1/4-28 screws, leaving them loose enough to allow the unit to be moved into it's final position on the buffer tube.  The front edges of the main housing should just butt up against the upper spade grip frame and the sides need to be parallel to the sides of the back plate.  When it all looks nice and square with the back plate, carefully snug up the clamp bolts working evenly between them (tightening one side more than the other tends to cant the unit on the buffer tube.)  Also pay close attention that the front edges of the main housing stays parallel to the back plate in the vertical plane.  When you have the unit square and parallel with the back plate surfaces, tighten the clamp screws securely.

9. Turn the assembled unit and back plate upright and loosen the 7/16" jam nut on the rocker arm adjustment screw.  Back the 1/4-20 adjusting screw out until it just touches the back plate trigger.

10. Reinstall the back plate assembly on the gun.

11. After making absolutely sure that the chamber is empty, charge the gun and rotate the crank enough to cause the cam to trip the rocker arm/back plate trigger.  Listen for the sear to release the striker (It probably won't at this point.)  Assuming that it doesn't, turn the rocker arm adjusting screw in (clockwise) a little and rotate the cam past the next lobe to see if it trips the sear.  Repeat the process until the rocker arm reliably depresses the back plate trigger enough to achieve sear/striker release.