Micro tools sells a "pull the leader out" device.
Search for 'film picker' on the evilBay and there's a bunch for a buck or two. Their operation is not flawless, but almost so. I've got several laying around my place.
If you bulk load your own cassettes and foolishly cut the corners of the tail square you'll never get it out with one of these. The sharp corner will catch on the felt light trap. But if you round it like the commercial guys it will work fine 99.9% of the time.
There's a reason many mall one hour joint in the USA, and who knows where else, had some of these laying around. Once you've done it a couple of times even an imbecile like me can do it.
If you ever went to pick up used cassettes from a one hour joint to get 'free empties' you'll see that the film was extracted through the felt and cut at the end. The film picker is what almost everyone used to get the film tail out to feed into the machine. They didn't break open the cartridges. At least that's what I found in the places I checked out.