My bad. It required no assembly, so I never read those!
Here is what Dillon says in their "Accessories Manual." No mention about what material to hit it against!
"IMPORTANT
For use on CENTERFIRE CARTRIDGES only. Not for use with rimfire
cartridges or explosive-projectile ammunition.
Before you begin make sure the FLAT side of the metal chuck assembly
sits on the flat surface of the puller body and the cap is threaded on. Also
note that the rubber strip is crimped to the chuck jaws, it is not a ring.
TO OPERATE: Loosen the cap until the chuck inside of the cap loosens
enough to easily insert a round. Insert and rotate the cartridge until the
chuck engages the extractor groove or contact is made on a rimmed cartridge.
Now tighten the cap.
Grip the handle mainly with your thumb and forefinger. Easy extraction
results from the handle shaft being PARALLEL to the striking surface AT THE
MOMENT OF IMPACT. This also protects the plastic head from breaking.
Rap the nose of the bullet puller against a hard, solid surface. If more than
one rap is necessary to extract the bullet, retighten the cap after each rap.
Remove the cap to retrieve the components.
NOTE: To protect the lead tips on soft-point bullets you may want
to place a foam ear plug into the nose of the bullet puller prior to
using the bullet puller."
To be honest, I think the hockey puck idea is one of the best yet. I may improvise as I have some round industrial plastic pieces that I can use instead.