My first Contender was sent back to the factory 3 times for misfires. 22lr, 35 Rem, 357 Max with factory loads or reloads all misfired. After I had it pointed at a deer one day and it misfired I called T/C madder than a hornet and asked to speak to the Service Manager. After a few minutes of discussion he asked me if I was using a hammer extension. I said yes and he said that the spring in the contender is marginal with some primers (magnum rifle primers) and that the hammer extension adds just enough weight to mess things up. He told me I had weakend the spring to send it in and he would change the spring the day he got it. Got it back in about a week and they even put a new wood grip on it since the old one was scratched (peace offering I guess). Anyway, 8 years and no hammer extension latter, I have never had another misfire with the 9 calibers I currently shoot.
I know a lot of people use them, but from my experience my Contender will never have another one. You did not say if your gun was a Contender or Encore, I hope Contender after this long post.