Started with factory trigger, SA pull measured ~6lbs with multiple tests.
Noted that there is a surface coating on all internal parts, probably to inhibit corrosion, but this coating is not smooth and contributes to the gritty feeling with trigger take-up and pull.
Installed MCarbo trigger, polished all surfaces on trigger bar that contact other surfaces or gun internals. Polished trigger bar disconnect or, all 4 sides where it slides in the insert rear to reduce sliding friction. Lubricated with CLP and reassembled gun.
Tested trigger pull and consistently get 4lbs pull. Still feels a little gritty on take-up, but much better than it was. The overtravel and take-up were reduced to desired range and set screws lock tinted with blue to hold set.
Very happy with results!