I've found you really have to stretch it. Not like stretch it to break it, but just give it a few good yanks to stretch it out. Like others said, if you are using beads that are not totally smooth inside, it can snag and break. I have successfully crimps on stretch magic, so it can be done, but everything must be smooth! Get a small container of water, wet the reamer, and go back frequently to wet the reamer. This works really well for me. But forget doing semi-precious chips. NIGHTMARE!