This is a tribute to the Episode of Alabasta. Barney may be good with guns but those won’t be very useful against Luffy. In fact, no weapon that Barney has will be of any use here because Luffy’s haki will absolutely be enough to block every move. There’s just no defeating a fighter this powerful and Barney’s about to learn that the hard way. Good luck trying to defeat the man who will become King of the Pirates! Luffy wins.