Went out to the range and did some intensive practice with my .40 S&W 4013(non-TSW) and noticed that my aim has to be at a 12 o'clock hold. This is consistent using factory loads as well as my hand loads. The sights are factory night sights, unaltered by me at all. Horizontal plane is perfectly fine, it's the vertical that provides the problem. Edit; The range was a flat 20 feet, I was sitting at a bench, fully supported. Shots were controlled aimed. Edit #2; I was having to aim 6 to 8 inches above my target center. At 20' I find this odd.