I was just at the range tonight. I should 200 rounds of Monarch 9mm. My C9 didn't like it too much. She gagged on a lot of them. In addition, almost every round key-holed (went through target sideways). I might have a target still that I can scan to prove it. It was a great price, 4-50 rnd boxes for $27 and some change. However, the key-holing slugs worried me that I might damage my C9. The gun range guy said they wouldn't hurt it, but I don't know. Anyone have experience? If it won't hurt my baby might go ahead and keep buying them for plinking.