I have been unable to find any information on this topic, so I look to more experienced people. I've seen a good bit of information on the signs of overpressure on cartridges, such as the flattening of the primer, etc. What about when a round doesn't have as much pressure as it should? I ask because I was shooting some reloaded 9mm and noticed that there was some soot on the outside of the brass near the case mouth, almost as if the case wasn't expanding fully in the chamber. The rounds were loaded with Hodgdon Universal to the minimum powder amount and did cycle the slide, but sometimes the slide wouldn't stay open on the last shot. These are the reasons that lead me to think that my rounds may be a little underpowered. Any suggestions, remarks, or comments?