I don't have my notebook available right now, but when I compared my 9mm AR15 to my SIG p226 the 16" carbine barrel always gave a higher velocity.
If memory serves, the 115 grain bullets would usually pick up 200 fps from the carbine. 147 grain bullets did not enjoy as much of a boost, but since energy goes up by the square of the velocity, this is understandable.
My SIG is kind of slow, but my carbine will shoot everything at a higher velocity than I have ever seen from a conventional pistol. The highest velocity 9mm pistol I have ever clocked is a 5" Colt Gov't model. The AR-15 handily outperforms it. This seems to be the case with light, standard, and +p loads.