IIRC, generally, expansion is reliably ensured at ~850 fps. A Speer tech said I should expect "about 920 fps" from the 38 +P Short barrel load from my 4" barrel. I do prefer 3 and 4" barrels.
To me the craze for featherweight hand weapons in the 12-16 oz. range has gone a bit too far, regardless of the popularity. An all-steel gun at 20-25 ozs. and a 3" barrel and adjustable sights makes more sense, is easier to shoot, because it soaks up recoil better, and can be fitted with grips for everything from dainty lady's hands to Gorilla paws. I can carry my 42 oz 586 all day without a problem, but I would love a smaller gun...they are easier to conceal. Ammo? a good (read major manufacturer's) 110 gr, 125 gr., 135 or 158 gr loads, or an equivalent (practice) reload that will get beyond minimum expansion velocity in a barrel will be all someone will ever need...IF they practice with it! My HBWC reloads all were traveling sideways by the time they got to 25 yards!