Why did Taurus start putting the serial numbers on the frame, barrel, and slide? My PT111 Pro has them in the three locations as does my PT145 Pro. My friends PT111 Pro only has the number on the back of the frame. Manufactured in 2003. So if you need to replace a slide or barrel or whatever, either your numbers won't match or you get blanks. Anyone know the whys and hows? Kinda curious and got me to thinkin'. I know, dangerous thing thinkin". ???