I've used both primers in my 500 Linebaughs which are basicly identical excdept for the .500 vs .510 and both have worked great for me. I used to use only the Winchesters since they are dual purpose, as you may already know they are good for either standard or mag loads. I've never noticed any difference in any of my big bores between the two primers, when there was as shortage after obummer was elected the first time I bought several bricks of CCI since it was all I could find and I switched everything including my 44's 45', 454's, 475's and 500's from the WLP's to the CCI's.