A good example of "Good things aren't cheap, and cheap things aren't very good". If a company puts a warning and suggestion in the case with the gun from the factory, I'd adher to it. As the reports above warn, you can get anything from short stroke, burning residue kicked into your face, or worse if those rounds are used. I use the Winchester Super X and never have a problem. I have some Hornady Critical Defense coming for use in another weapon, but I'm going to see how my PMR30 likes it too. Most reports on this forum are positive, so we'll see. But my first pick is the Super X. Good luck!