Luffy Uses Culverin Statistics Japanese Name: ギア4（フォース） 弾む男（バウンドマン. Fighting Style Focus: Fists, Rubber body, Inflated muscles, Limbs compression, Haki For the chapter of the same name, see Chapter 784. Gear Fourth: Boundman is a technique first seen in Luffy's battle against Donquixote Doflamingo.It was developed by Luffy during his training on Rusukaina. Gomu Gomu no Culverin (ゴムゴムの大蛇砲（カルヴァリン） Gomu Gomu no Karuvarin?, literally meaning "Rubber Rubber Great Serpent Cannon"): Similar to Afro Luffy's Gomu Hook, but improved. Luffy delivers a punch like a regular Gomu Gomu no Pistol, but if it is dodged, he can redirect his punch an unspecified number of times, without losing momentum, to still land with tremendous force. In addition, this punch does not need to retract back to his body right after being "fired" as the regular Gomu Gomu no Pistol does.A culverin is a relatively simple firearm, ancestor of the musket and cannon.