not sure if it's the same as the LG300, but the way to set them for sear disengagement is to cock it, and turn the screw until it fires, then back off 1/4 turn... mine is actually more like an 1/8th, but whatever floats your boat.

really not good practice to have it light enough that it could go off like that... you could slip or something and release a shot without control. I'm sure that's me trying to give granny an egg sucking lesson though...