CCI Bench Rest Primers are continuously tested and improved. As a result today's CCI primers are more sensitive, easier to seat and more compatible with progressive and automated loading equipment than ever before. They utilize modern non-corrosive and non-mercuric initiator mixes for the cleanest burn possible. CCI knows that bench rest shooters need reliable components that offer match-winning results. Each primer is marked with a "B" so they are easily identified next to other primers.