Just curious,what make?does that plastic trigger have an OT screw?and why wouldn't a decent after market replacement work without substantially changing anything?
Colt Series 80.
If the aftermarket trigger's bow length differs from the OEM trigger, the trigger bar lever and the plunger lever won't be in the same position when the trigger is pulled, and there's no way of knowing until the trigger is installed and the firing pin release timing is checked.
It can go either way, depending on the new trigger's specs. It can just as easily correct a slow timing issue as cause one.