The hammers cock fine when I lift up on the hook that hooks onto the pin in the underlug. When I put the barrels on and open them, the underlug pin is not catching the cocking hook and thus is not lifting up and cocking the hammers. With the side plates off, everything looks good and clean and operable. Is it necessary for the forearm to be on the barrels in order for the underlug pin to catch the cocking hook?