I'm working on this with Kes right now. So far, I'm having a LOT of success with running away from him after the pick up - he has to basically chase me with the dumbbell in his mouth. This seems to be building nice speed on the return *and* a more solid hold.
When I stop, he's basically shoving the 'bell at me with a nice calm hold, so I'm gradually adding in a little duration before I even touch the 'bell. Sometimes I add a little tugging into the process as well, to take advantage of opposition reflex. Clean fronts will come later.