It cracked the choke down the middle, but not the barrel. I am sure that with the right load it will blow up the barrel, I got lucky. Personallt, I DO NO LIKE THIS SYSTEM. I have talked about it on here, and have E-Mailed Thompson. A better system, would be to have a semi-external choke, like a Turkey choke for 12 gauge, one that you could see clearly to identify the choke being in. The present system is stupid and very dangerous.