Quote Originally Posted by nak81783 View Post
I've often wondered about this. Let's take a little tangent while we wait for the OP to reply.

First, I agree the gap has to be there, or the marker may not complete a full cycle. However, since the chamber is pressurized (pushing on the top of the pin), and the bottom of the pin is at ambient pressure, wouldn't the pin continue to push down until it hit a positive stop (back of sear) regardless of on/off type? If so, I would argue that trigger rod adjustment is more to accommodate the body/rail/trigger frame stack up than a different on/off type.
My understanding is if the sear rod hits the back of the trigger it is essentially keeping the front of the sear from catching the bolt. Once the front of the sear catches/hits the bolt, than the sear rod stops moving forward. If it's too far back, the trigger cannot push it far enough back/up for the sear to fully engage the on/off pin. The on/off pin stops when the sear stops, which stops when it hits the bolt.

With a ULT, as you add shims it pushes the bottom of the on/off down, pushing the back of the sear down and the trigger rod forward. So as you add shims, you have to turn the sear rod in/away from the trigger to maintain the gap.

Correct me if I'm wrong.