I am not sure where their locks come from but my Tradition's and CVA traditional rifles have that same round bolster that is bolted into the barrel. Do not remove the bolster clean out screw. They only seem to get deformed and do not come out well. Also the thing I dislike about the round bolster is BE CAREFUL putting that nipple back in. For some reason it seems real easy to cross thread. Turn that nipple in real slow and back off if it balks.