SK,
Glad to hear you were taken care of and got a replacement revolver. I almost hesitate to share my experience because in spite of it I'm sure you've got a fine revolver. It would be incredibly bad luck to get two "lemons" in a row, and properly made the SP is a great revolver. You made a good choice.
My SP started out with the barrel rotated too far into the frame (sight was so far off vertical it shot inches to the side at a few yards after I got it to the range). It was very obvious. Mea culpa! I should have noticed it before I bought it NIB at a gun show from an out of town dealer.
Sent in to Ruger and it was returned to me with the barrel unscrewed to fix that problem (the repair slip said the barrel had been "repaired"), but the barrel cylinder gap opened up to 11-12 mils as a result (6 of which was end shake). I expect some flash out the gap, but this one got to be a bit much and I wasn't excited about the velocity loss either.
To Ruger and back again with a replaced cylinder and no improvement in gap or end shake. Ruger insisted it was returned with a 6 mil gap. I went shopping and looked at a couple other SP101's closely-all had nice tight gaps. I also noticed their hammers didn't swim around in the hammer well. The hammer well on mine was machined too wide, almost down to the end of the hammers travel, i.e. a lip was left on one side of the frame where the hammer face strikes the frame.
I sent it in the third time with a peice of my feeler guage cut off and resting in the gap. It came back with the barrel replaced, the gap down below 6 mils where it should be, and the remaining lip in the hammer well machined down.
The replacement cylinder from trip number 2 was no beauty-the primer ends of the chambers are very roughly ovaled out in an attempt to flange up the chambers with similiarly misshapen ejection star openings. But it seems to shoot OK, rounds slide in real easy even if they do rattel around a bit in the cylinder, and I'm worn out dealing with it. The revolver is at least at the point where I would not feel guilty selling it used to somone, and I may hold onto it.
I've seen SP101's with fine workmanship, and then there's the one I carelessly purchased NIB without looking closely at it first. As I said before, I'll never purchase another without a very thorough going over.