I had an epiphany yesterday. I had a flat, and I was a little nervous using my CO2s since I recently had a flat and couldn't get the gas in the tires. Used my 2 cartridges, then took a ride from a kind stranger (which I really try to avoid).

Well, yesterday the CO2 gods shined upon me, and all the gas went in without trouble. I then went to the lbs for a new tube, and I always ask for short stem, which work best with my floor pump. They happened to be out, and the lbs guy said I like the longer stems anyway. The short ones are about 2 mms short for my cartridge adapter. Doh! That was my issue!

Oakleaf, I like the advice for the partial inflate before wheel install. I'm going to do that next time. My bike has horizontal dropouts, and it's a really tight fit. I often get jammed during the install when the tire hits the seat tube. I bet that will give a little extra room that I need.