It reduces vertical recoil on firing. The Rhino and other bottom-barrel revolvers (like the Mateba that I mentioned) are obviously what inspired the design of the hand cannons in Destiny. But the hammer mechanics are wrong. If the hammers are fully functional (which they appear to be, based on the in-game animations for ALL revolvers, including The Last Word), then the design of the hand cannons themselves are wrong. If the hammers are not functional, and are false hammers as seen on the Chiappa Rhino, then the animations are wrong. Take your pick. Either way, they're wrong. lol