From memory, they can be a bit loose, but it doesn't really matter, as long as they're engaging properly. It's just a question of striking the balance between trigger responsiveness and accidental actuation.
I have found the easiest way to adjust it is to build the gearbox in gun, etc and then take the rear lower stock pin out. This usually allows you to pivot the pistol grip/trigger mech from the front pin and adjust until you're happy with it, by bending arm/moving the trigger grubscrew in and out. The advantage to doing it this way is that you can hear/feel the microswitch actuating (make sure the battery is out before you start all this!) if you've done it too tight.
I also find it worth backing off just a little anyway, because there can be a bit of flex in the fittings and if you've got it adjusted too finely you can end up firing when you lift the gun using just the pistol grip, because the weight pushes the pistol grip/trigger assembly up into the main body just a hair.
