Hodgdon's reloading data says they used WSR primers for 454 Casull with H110. Am email from Winchester told me that "you cannot use small rifle primers with a 454". Go figure that one. I was loading 300 gr boolits with H110 and ran out of CCI SR Magnum primers but I have some Winchester WSR primers and I see that Winchester makes a large rifle mag primer but not a small mag. I have read that a lot of you, here in this forum use and like Winchester primers. My query is, has there ever been an independent test of the brisance of small rifle primers? Evidently Winchester thinks theirs is hot enough to not need a mag rating. I know that years ago the early Speer manuals recommended mag primers for all ball powders. I used mag primers in my 223 with BL-c2 and the accuracy got better and velocity spread went down when I did.