Umm, while Rumple's idea worked well it seemed a bit too much effort...
How 'bout some 5 minute epoxy...
Take the spring (the size Rumple mentioned sounds perfect) and dip one end in a generous amount of the glue and stick it to the ball (roughing the surface with some sandpaper first would help), after that dries well, take one end of the dowel and dip it in the glue, and glue the dowel inside the spring. Now you have a weasle ball permanantly mounted to the dowel.
The other way one could do it is to glue the spring to the ball, and get a piece of rubber hose that fits on the dowel (glue it in place on the dowel) and the spring can be shoved down inside this piece of rubber hose... now you'd have a weasle ball not pemanantly mounted to the dowel (and you could use a long dowel in deep cover and a shorty for stubble fields... the weasle could then be put away in a pocket or pack, and the stick rubber banded to the side of your gun barrel, and then your hands are free to do whatever between stands.
I hope this helps,
Jeff /ubbthreads/images/graemlins/cool.gif