Best price for this geissele trigger is at optics planet - Geissele Hk Mr 5.56 Trigger

I'm always looking for the best deal possible; Optics Planet had the best price for this trigger, Defense Depot had the best price by far for the MR556.
The rifle comes with a good trigger, the Geissele is better. The spring design of the Geissele trigger/disconnector portion is more robust and will likely never fail or become compromised by sand or gunk. Release of the Geissele hammer is crisp and more predictable, with only a trace of creep. Keep it properly lubed and it will remain your favorite trigger for this rifle.
Removal of the H&K trigger is a little tricky. The hammer comes out in the usual manner. The trigger/disconnector must be shifted forward to clear the safety, then pushed up and out. There is a silver "clip" which holds this assembly in place by friction even after the pin is removed.