Being able to eliminate pre-travel for the MK3 was terrific, but as soon as I took it out at the range, I noticed that half the time the trigger wouldn’t reset. The remedy was to either push the trigger in reverse direction and wiggle the trigger to engage the reset, or simply tune the trigger reset way back, leaving a large pre-travel again.
After many hours of inspection and assembly/disassembly, I start to notice that there is this click on the trigger’s pre-travel that only happens if I lean the trigger towards the left. I also noticed that the sear had no problem resetting, it was the trigger disconnect bar that’s causing me problems. The trigger disconnect wasn’t rising to the top to engage the sear. Something was getting it stuck.
In previous attempts to lower trigger pull weight, I also took note that if the trigger’s plunger spring is installed incorrectly, you would hear a slight click noise coming from the plunger spring also. In this case we’re definitely looking at something else.
As it turns out, the culprit was the magazine disconnect spring. It was sticking out just enough to rub against the trigger disconnector. Not only would it cause a clicking sound, but it was also causing some friction on the trigger disconnector.
The remedy was a simple matter of clamping down the spring’s hook so it doesn’t stick out, and as a precaution I also grinded off the corner, but that shouldn’t be necessary.