I chronographed the Speer 135 +P Gold Dot in my 642 and got 842 fps.
At 7 yds it was "accurate enough", but not outstanding.
I also carry a 640-1, 357 mag, and load Rem 158 gr 357 mag SJHP in it. Chronographs at 1140 fps from the 2 1/8" bbl. It was very accurate at 7 yds.