A little more research dug up this:AndyC wrote: More velocity - hmm, that's debatable. A longer barrel doesn't automatically mean higher velocity - especially if the ammo is regular factory off-the-shelf stuff that has been tuned for the average 5" handgun barrel, the longer barrel might even slow the bullet down.
http://www.ar15barrels.com/tech/9mm.gif
Which looks like even an increase from 6" to 16" barrels only result in a 200 fps velocity increase at best.
So the velocity increase alone doesn't seem to be as much of a factor as I thought it might be..
Edit: which seems to indicate to me that you should just SBR that uzi down to a 10 inch barrel or so and maybe start to eliminate the negative of it being hard to operate with that extra bit of barrel sticking out.
