Mike, can you link to the actual specific Trijicon HD rear sight you used? I'm also interested in swapping out the rear for the very same reason as you.I have the 9C and the P320 FS. Both are great pistols, but the 9C is my EDC, while the P320 is on standby. Either will do the job, I just kinda prefer the grip on the FNS for an EDC gun. The only thing I did to it was stone polish the firing pin blocker ramp and swap out the rear sight for a Trijicon HD rear, and swap the stop mag release bar for one from a full size. I didn't like the stock ramped rear sight in the event a single hand manipulation was needed.