While not S&W, the last time I sent a gun back for warranty repairs it took almost 6 months of excuses, having the wrong gun shipped back to me (I sent a pistol back, they sent a shotgun back to me), more excuses about why it was taking so long, promises it was going to ship at the end of the week, etc., etc., etc.
I finally told them I wanted it back, fixed or not, I got it, I had aleady ordered the parts (broken firing pin) and when I got it back (still broken) I fixed it myself.
That was the second time I let someone else work on one of my guns. Never again. Never. I've got this funny thing about incompetence and being lied to.
Sorry. The initial idea was to agree the APEX parts work and make the trigger much nicer which improves the shooting experience and makes you like the gun even more.