That is an odd looking Ruger! Seems that if you wanted to go that way, a Contender would have been cheaper and easier. Of course, Contenders don't even come with one cylinder, let alone six.
To your question: it depends on the gun. I've done a 12" group with a GP100 6" and a box of ammo offhand at 100. And I've sniped milk jugs at 300 with a 6" Sauer single-action off my knee. Right now, with no warm-up, 100yds. After a couple cylinders to warm up, with good light, probably to 200, off my knees.
