A press will make short work of it but it is doable with other tools. Take a notched piece of steel @1/4" thick to support the FSB on a vice. Take a 1/2" shoulder bolt and grind the threads off (to work as a pilot). Use either brass or copper washers to go against the crown and hammer out the barrel from the FSB. To install support the barrel at the GB and tap the new FSB, drill and pin. Done.