I had one that would misfire with Rimmed or Rimless cases, Centerfire or Rimfire. T/C blamed it on the hammer extension. I laughed. They changed the springs for the third time, but this time I did not put the hammer extension back on. 8-9 years later, never had another misfire. Know a lot of people use em, I still can hardly believed it caused it, but after the last 8-9 years, not gonna use another one.