Often just a hardwood dowel is enough. The brass rods with the hardwood handles that H. Richard posted look pretty nifty; if you were to put the rod right through, exposing it at the end and pinning in place, you could use a mallet if hand pressure wasn't enough. I've seen the rods Brownells sells but at $30 apiece (!?), they seem a very expensive option.
As H Richard said, it makes for a heavy range bag, but better than having to drive home with a jammed up gun. And like battery cables in the car, there's a good chance that someone else may need it even if you don't.