I just put in my Apex flat faced trigger kit. I too had accuracy issues, I first blamed the gun then I did more research on grip and trigger technique. Groups where much better after more practice just like anything. Now I have shot about 500 rounds through the gun and no failures. Main reason I went and bought the Apex trigger so quick was I shot a buddies Core with Apex internals and stock trigger, 3pounds area. Best group I have ever shot and it was with a .40S&W. I will let you know if the Apex flat trigger is just as good. BTW its sells for $157 Prime 2 Day shipping through Amazon. I also went ahead and bought an Apex armors block from Amazon for like $28 Prime 2 Day shipping. Off Apex's official site Flat Faced Trigger runs $180 shipped, for $5 more you can get an Apex Armors block with the trigger kit on amazom.
Shot the set up this morning and was night and day difference. all my shots were within 2inchs from each other some much closer and in a 2" circle.