Update on Apex spring kit and Apex Enhanced Trigger Kit
I recommend installing both the Apex Spring Kit and the Apex Enhanced Trigger Kit. At first I only installed the spring kit. While the spring kit worked as advertised, and reduced the trigger pull a great deal, perhaps by half, I was not completely satisfied with the results. Perhaps my shots improved somewhat, but that long trigger pull still made me anticipate when the trigger was going to break.
I feel the Apex enhanced trigger was well worth the money. Apex advertises that it reduces the pre-travel by 20% and the over travel by 10%. I think that it reduced the pre-travel a great more than what they advertise, perhaps by as much as half, but it could also be because the trigger is more comfortable. The enhanced trigger also reduced the trigger pull weight by at least another 10% more in addition to what the spring kit did.
The safety on the Apex enhanced trigger is like that of a Glock. On the stock trigger the entire tip or bottom half of the trigger was hinged, so I never could understand how the safety actually did anything to prevent a miss fire if snagged on clothing or something similar. Therefore I think the enhanced trigger is somewhat safer, but the only real safety is between the ears.
The only hard part about installing the spring kit and the trigger was getting everything back together. I had trouble getting everything lined up, especially getting the trigger return spring through the slave pin. It didn't go any easier the second time when I installed the enhanced trigger.
Everything tested out fine when dry firing, so it was off to the range to try it out. First shot was fine, but when I tried the second shot the trigger was dead. The trigger was not capturing the sear. (See picture below of properly captured sear.) With the slide off the frame, the trigger would return and capture the sear, but with the slide installed on the frame, it would not. The trigger did not have enough return to capture the sear when actually firing.
The one thing good I can say about my Sigma is that it is very reliable. I have never had one failure of any kind, and I want to make sure it stays that way.
I ended up using a fine emery board, to file a very small amount of material off the front part of the trigger where it makes contact with the frame. (See second picture) I did not have to remove very much at all, probably no more than 1 or 2 hundredths of an inch. I was able to do this with the slide off, but without removing the trigger from the frame. With everything testing out fine, it was back to the range.
After sending about 50 consecutive rounds of lead down range, the trigger stopped resetting again. I think it probably had something to do with the gun getting hot. I field stripped it and took a little bit more material off the front of the trigger. It didn't take long for me to send 100 more rounds down range, with everything working just fine.
The trigger made a world of difference. Nice crisp break, and much smoother than before. My accuracy defiantly improved, but not as much as I would like. Time will tell.