In making comparisons between two different guns, the bore of one might be .354, the other might be .358, the leade diameter and length could be vastly different. One may have rough machining marks, the other highly honed.
In the earlier link, someone cut down a barrel and checked velocity at different lengths.
http://www.ballisticsbytheinch.com/9luger.html
Gleaned from that data:
Corbon 90gn, highest velocity @ 15", next highest at 17". Velocity @ 18" faster than 16".
Corbon 115gn, highest velocity @ 17".
Corbon 125gn, highest velocity @ 13", next highest @ 18". Go figure.
Corbon 115 DPX, highest @ 16".
Federal 115, highest @ 17".
Federal 135, highest @ 17".
Federal 105, highest @ 17".
Federal 124, highest @ 17".
Federal 147, highest @ 17".
Speer 124, highest @17".
But they all had a pretty flat velocity curve starting around 12-13". Being that these were all defensive loads, and some were +P, I bet they all had slower burning powders to get as much velocity as possible. I would not be surprised if really fast burning powders, like N-310 or Nitro100NF would start slowing down at some distance less than 16".
