I've had a ported 3" 65 since the mid-80s...... it was the hot mod from mag-na-port.

Then all the arguments above on both sides started... first in the 'Gun Rags" and then the internet........ with no one changing the other's mind on the subject......

S&W Performance Center put out a "dozen'' or more ported/expansion chamber short barreled revolvers in the 90s and beyond.

I guess I'd come down agreeing with Colt_SAA arguments.....

I saw improvement with muzzle flip when shooting full bore .357 magnums.... but as I generally carry +P .38s in my 65..... if I had to do it over again ...... I'd probably pass.