I've used them and in fact bought another thing as I saw them on sale at Wal-Mart for $4.50. The only others I've used on my muzzle loader that uses #11 caps is Remingtons and I've had several mis fires with them. I've never had one to my knowledge with the Winchester. However, I figured out that once I clean it I need to fire a few caps through it before loading it up. If I do that I've had good luck with both the Remingtons and the Winchesters. Not sure I've ever tried the Winchesters without doing that after figuring out that was my problem with the Remingtons. I have a Marlin 50 caliber muzzle loader I'm shooting them in and they work just fine. I like them.