Sterling silver jump rings, whether you make them yourself or buy them pre-made will be in a "dead-soft" state. That means the metal is relaxed and the wire is very easy to bend or form. It also means that when the jump ring is used to connect pieces, the slightest tug or catch on something will open the ring up and you can loose your parts. The solution is to work harden the metal by tumbling. Tumbling stiffens up the wire without distorting it or changing the size. Watch how easy it is to work harden sterling silver wire in the tumbler.