Right on, Pugsy.
I bought the HF stud gun kit in 2010. It was crap, not very effective but only a hundred bucks. I'd give it to you if you were nearby. A decent stud gun is more like $250 and most won't come with a shrinking tip but its only about ten bucks more. Easy to find demonstration vids about that on the web, and you may find them interesting. Of course I'm not suggesting that you go buy a brand new one for one stretched panel. It may not be a technique that finds favor among enthusiastic metal shapers but it can be a lifesaver during a person's learning curve. So did you try shrinking with a small weld on your practice piece?