This is the end of my Sigma's journey. I recently bought a new striker spring through Wolf Spring. A lighter than stock replacement spring for the Sigma was a 3.5 pound spring. Stock is 4.75 pound spring. Heard of light strikes with 3.5 spring. I installed a 4# spring made for a Glock. The spring measured 1" longer than stock spring. Installed without a problem. Trigger is lighter, not by a whole lot, but lighter. Still planning to use as a carry so I don't want a light trigger, besides the Sigma is not my idea of a target gun. The pull is more like a stock Glock, maybe a tad heavier.
Will be taking to range to test. Will get back with results...