After trigger is installed, depress trigger and look in rear of receiver, primary sear should be flush or below receiver. If not see instructions.

With upper bolt and hammer out of receiver, depress trigger just enough to take up play and slide stop against trigger and tighten screws. You must leave a small amount of play or secondary sear will not engage.

Primary trigger stop
Install between trigger guard and housing.

Depress trigge and check clearance, the supplied paper clip should slide through. If it doesn't you will need to file the secondary stop to give it the proper clearance or trigger will cause double firing.