The crimps available at the tackle shop come in several different sizes. I usually buy the crimp one size larger than neede so I can loop the loose end of the leader back through the crimp one more time. This is something I learned while sturgeon fishing many years ago to be sure you're leader didn't come apart when hauling in one of the big'uns

I have used bronz tubing when in a pinch, but I feel better using the steel crimps just for piece of mind.

John