I went a little different route with my rifle nipples. I just removed them and took a couple strokes on the end with a file to put a slight burr on the nipple. It really holds the cap in place where you need a knife or similar to get it off. Firing it off there is no issue as the cap splits as it normally does.
It might work on a #10 nipple using #11 caps.
It might work on a #10 nipple using #11 caps.
