CCI primers are less sensitive* than any other brand of primer, if your hammer spring is marginal it can cause failure to fire problems, so if you get primer impact and the shell doesn't fire, then you need to fix the rifle for more impact force behind the firing pin, or switch back to the Winchester primers.
*Less sensitive means it takes a harder impact to set them off, a lot of people think CCI primers are harder, in fact the difference is sensitivity not hardness.
