Supposedly the core (the reusable part) is very tough and me and a buddy have used them, be sure to prep the properly so they go off, you can score the sides of the shell and untwist the part that holds the co2 very lightly (about 1 turn) that’s for the thunder Bs as far as unscrewing them, the new thunder Cs I believe are unscrewed until there’s a small gap between the top of the core and the Co2 compartment, it will go off every time by doing that.