Those more knowledgeable that me can correct me if I am wrong here but it can be confusing around 9mm and power factor.
9mm is generally Minor power factor but can be Major PF in open guns. I *believe* the difference is the case, Minor is 9x19 (by far the most common for 9mm) and Major is 9x21.
9mm is generally Minor power factor but can be Major PF in open guns. I *believe* the difference is the case, Minor is 9x19 (by far the most common for 9mm) and Major is 9x21.