I shot a small (71 lbs dressed) doe at the family ranch with a S&W 6" 686. The load I used was Fiocchi's 158 XTP. Range was 22 yards. Please understand that 71 pounds is an above average doe in our neck of the woods (average mature doe size is ~68 pounds).
The shot was nearly perfectly broadside. The doe buckled strongly to the shot, ran 35 yards, and crashed to the ground. I could see where she fell so I walked up to her and put her down and she was breathing her last.
The bullet entered her right side shoulder just behind the leg bone. The bullet continued throught he ribcage and exited the offside shoulder. Exit hold was also just behind the leg bone. I'd estimate bullet penetration in the 12" range. Heart was destroyed. How much the bullet wound have continued to penetrate? Who knows. There was some blood shot tissue, especially in the area between the front shoulders and the rib cage. In the attached pics, the front leg was extended southward as the deer was hanging by its rear feet.
Bottom line: I'm very pleased with the penetration. Expansion was NOT dramatic at all which is to be expected with this caliber/weight combo in .357. I wish I'd have put some type of reference in the photos to show their size. I'd estimate the exit hole was between .45 and .50. This load shoots lights out from my revolver and penetrates like crazy so it will continue to be my deer load.
I've got two photos uploaded below and all four in my profile. I'm still working on this photo attachment thing.