for me the antler works better on things like obsidion,dacite,novaculite,keokuk
and the copper works better on things like rhyolite,kentucky blue,coral etc
but im not a real experienced knapper as of yet,only been knapping a couple of years now
and havent had a real lot of varieties of rock
i live in minnesota and have to buy/trade for all my rock so i dont get to try all that many differant ones