I have to admit, the 9mm barrel isn't as accurate as I had hoped. With the limited amount I have shot it (12 different loads incl 115, 124 & 147gr w/various powders), the best group I have gotten is 1.8" at 10 yds where my 5906 does under 1" with the same loads. I've tried several and so far they all seem to average 2.25-2.5" at 10 yds. I keep hoping to find that one decent sub 1" load but I am starting to think that might wishing for too much. I would like to try one of the 3rd party barrels just to see if there is any improvement possible in this gun.
My XD's have always been tighter grouping than my M&P (in .40) so I may get a 9mm barrel for one of them to see if it is any better.