the front screw adjusts the sear engagement, and sets the trigger for two stage operation, to adjust the sear remove the stock and turn the rifle upside down, under the adjustment screw lever (yours has a black screw and silver nut) you will see a rounded part this is the release for the piston, push down on this part and it will set the trigger. you may need to tap it with a punch to get it to set...once set look in the round hole at the rear of the trigger group you will see the other end of the adjustment lever and the sear, as the rifle isn't really cocked you can now gently pull the trigger and watch the parts move, the trigger should go back and then get to a point where it stops, the sear should now be almost ready to disengage, a little more pressure and it should crisply click and fire the trigger. to adjust the amount of engagement on your rifle loosen the stop nut and to increase the amount of engagement turn it counter cl;ock wise, to reduce it turn it clock wise. Make sure the stop nut is tight after adjusting. If the trigger comes back and doesn't get harder to pull just before the sear releases add more trigger weight by turning the weight screw behind the trigger in clock wise. If it is to hard to get the trigger to release then turn the weight screw counter clock wise, only turn about 1/4 turn at a time. The tigger group can be removed easily by tapping the two small 1/8th inch pins out and removeing the group from the action, the safety will pop all the way out and must be pushed back in to replace the trigger group. There is a very good primer on the trigger and tells how the entire rifle works at olympia.fortunecity.com/kickbox/377/xs-b20/xs-b20index
