When I first started using crimp beads, I used those corregated cheap ones. With crimping pliers they very nicely curled into a bean and closed into a round.
The silver tubes don't act that way. Rio has 1 mm crimps from .025" to .051". The little ones are so skinny, I would guess are just useful for fixing something in place on coated wire. Can only get one strand through them anyway. The largest ones look like they'd be the only ones that could accomodate 2 strands and still make that "bean" then fold over to a round. But I think I've also seen finished jewelry where the crimp is dimpled but not curled all the way over.
How are you-all crimping? Does anyone use longer crimp beads?
Tina