What was the charge and range?

I think those results are not unusual. The media you shot into are pretty "hard", and as I said I think the 250gr SST is a little "soft" (the SST and SW are the same thing). Especially if the range was under 100 yds, I would not be surprised to see the jacket separate. This is why I don't buy the "penciling" argument, I've seen way more real-life evidence of the opposite, that they tend to over-expand. I believe reports of this are why Hornady came out with the bonded version.

If I were going to shoot the 250gr, I'd definitely shoot the bonded version. With the 200gr I have also seen separation, but not nearly as bad, and not unless I hit both shoulders and recover the jacket under the offside skin (with animals DRT).