When taming or attempting to knockout the sling shot is your best option. You can easily get a knockout without taking damage by shooting while backing away since the carbonemys will begin following you after the first shot.
These guys are a must-tame for new players. They have tons of health, can swim and can be ridden as well. Do be careful though, hit it while trying to KO it and run! These turbo turtles will give chase and attack you. Use a slingshot to do the deed.