This morning a lady student came out to do some more break-in on a new Kahr CW9, so I set up the chronograph in advance and used the opportunity to do the testing below. The "standard velocity" shown is the same 124 grain load I've had in PM-9 for several years. The CW9 had only 100 rounds total of WWB down the barrel before the Gold Dots were fired. The other 2 pistols are far more broken in and were semi-dirty at the time.
edited to add: Sorry, I can't get the columns to format here, so just going to move "diffence" out by itself.
edited to add: that did not work either.

4-26-08 Gold Dot 124g 9mm
Std. Vel. +P "Short Barrel" Difference
Kahr PM-9 (2 3/4") 991 1,104 113 fps
Kahr CW-9 (3 1/4") 1,119 1,183 64 fps
Glock 19 (3.85") 1,121 1,222 101 fps