There's still the o-ring, but I thought it wasn't rubber?I always try to carry a spare o-ring with me when hunting, just in case. I've never had a failure due to the o-ring through several thousands of rounds, but I did pro-actively replace one that was looking a little ragged.
Um, no. My 11-87 uses the same o-ring as the 1100. I believe the main difference between the two models is that the 11-87 has a 3" chamber, whereas the 1100 is only 2 3/4".