front edge curl
Stan has the answer here.
Originally Posted by Stan. L-B
I shoot a lot of 220 as some of my panorama cameras don't take 120 as it's too short in length. It took a while to figure out it was the slight curl at the start of the film that was causing the jams in the reels. It's worse too with old film, it seems to have a tighter curl set into it.
So for me the answer was to clip the corners slightly and bend the front edge back and crease it, not too much though. Makes a big difference!