The K80 trigger blade is adjustable for position along a slide. There are two set screws on the underside of the trigger blade. The screw socket takes a 1.27mm wrench, 0.050″ or 1/20th inch imperial. The rearmost screw locks the blade onto the slide whilst the front screw locks the barrel selector positioned immediately in front of the trigger blade. There are two trigger blade types, standard position and forward position. The standard blade has both screws in front of the curved blade whilst the forward position trigger has one screw in front and one directly behind the blade. Function of the two screws is the same.
To move the trigger blade, slacken the rear screw but note that the front screw, if locked, will also lock the trigger blade. The front screw has to be far enough out to allow the blade to slide so if it will not move try backing that screw out some more. Occasionally, the blade will be stuck on the slide but is easily freed with a nylon drift. Make sure both screws are free before tapping the blade with anything. Once in position, tighten the rearmost screw to lock the blade on the slide.
To lock the selector, tighten the front screw until the selector cannot be switched left to right. To release the selector, simply slacken that screw off again.
Early K-80 adjustable trigger blades used a dovetail slot. Later models use a much stronger T-slot. Blades are not interchangeable between the two types.