I like a hefty 1/2" hardwood dowel rod for pushing .54 and .58 caliber balls down the bore when shooting at the rifle range.
The ones I make have a ball fitting brass tip on one end and a two-inch wood ball on the other.
Most hardware stores have 36" and/or 48" hardwood dowels. Pick one with good straight grain. Wood balls are available from craft stores and some building supply stores.
I put a two-inch section of 1/2" brass tubing on the rod by mounting it in a drill and letting it cut its way for about an inch onto the dowel while the drill is running. It gets pretty tight.
Then I fill the end with JB Weld. Cover the JB with plastic wrap, push a ball onto the wrap to make a form-fitting depression, and let it dry.
I make ball starters the same way.
Sometimes I use a seating gauge on the rod. It's nothing more than a 1/2" shaft collar from the hardware store with a nlyon washer glued to it to protect the muzzle. When the first ball is seated, the collar is moved to the face of the muzzle and secured with the set screw. Then all balls loaded after that (with the same powder charge of course) will be seated with the same amount of pressure.
