you didnt look in the thread that has cap sizes, but the new search isn't what the old one was. the eye is 16 and me, I kept the factory front as I tried two sizes BC caps. one was too big, the next size down was too tight. by that, it wouldn't snap closed if I pushed it all the way on as far as its supposed to go. I trimmed the cap of mine so it folded farther back and its working fine. the front bell is 2.319" inches. if you search "butler creek cap sizes" in yahoo you get a chart.