If all else fails cut it off just in front of the receiver ring then bore out stub..This last ditch method is used if the threads are severely galled..
But a relief cut just in front of the receiver works, never seen it fail.. Get as close to the receiver as you can with the parting tool.. .010-.020 should be good.
But a relief cut just in front of the receiver works, never seen it fail.. Get as close to the receiver as you can with the parting tool.. .010-.020 should be good.