Rant: "IC/AT" Recessed Lights; They May Be IC But They Are Not AT !!!

Okay, I recently started replacing several of my original recessed light fixtures with the much more modern "IC" (for Insulation Contact) and "AT" (for Air Tight) versions. I selected Halo Components if it makes any matter although all the available alternatives looked about the same to me. Although I can clearly see the way the IC happens (basically the design there is a can within a can) I honestly am amazed at how much air must still get through these things and I am stunned anyone could call these things "Air Tight". Now I know it isn't intended to be a big compressed air canister but seriously a somewhat significant 1/8 to 3/16 gap goes all around the outside of the can, the fixture tends to wiggle with any movement around the joists despite nailing down on all four arms, and there's another 1/16 to 1/8 gap that goes between the two cans!

I would think to truly be advertised as airtight they would have to have some sort of special sealant btwn all gaps and they also would have to be fastened by something to the topside of the ceiling. So because I basically didn't see dramatically better alternatives at my big box store, and also because I'm all done at this time with replacing the old fixtures with the new fixtures, I'd like to learn how to help make these things more airtight. I was thinking of this approach and would appreciate advice ... I have two extra tubes of Rutland's 600 degree Silicone Sealant and I was going to run a ring of this stuff to seal the gap that goes around the outside of the can (but not the gap btwn the two cans). I was also going to run a ring along all the edges that contact the topside of the ceiling to help hold it much more firmly in place and prevent movement. Is this the right approach and if not please make some other suggestions. Thanks!

Wow, thanks for that info and that all makes much more sense. I am also using LED's so I'm a little less worried about heat although I also read something that stated the original older non IC recessed fixtures with full wattage incandescent bulbs can be almost 300 degrees F at full temp! That's really really really hot! No wonder they wanted three inch clearance to combustibles! So I thought that the Rutland 600 stuff was just what I always want anyway ... "overkill, squared" ! As far as the "IC" rating, all the available options (I was only looking at 6inch fixtures for comparison) at both the box stores here have a "can within a can" design I don't see how they could be classified as IC without something that serves the same purpose. Are you sure that the lights you're looking at aren't formed from double wall material or something? Thanks Again.