I once ran a comparison between Win and CCI LR mag primers in my 7mm to see what differences they would make. What I found was that the CCI's averaged about 25fps faster and had about a 25% smaller spread in velocityvs the Win's. Both shot accurately and the difference isn't statisticly significant but I went with the CCI's anyway for that small addition of confidence. No complaints here with them. On the other hand my 30-30 load uses Win primers and I have had a couple that have not went off even after 3 tries at firing them, they had a nice dent in them from the firing pin but did not go off. Not sure what caused it but it makes me nervous about them.