Muzzle velocity design. In a side by side comparison with the .50 BMG, the titanium round "of any caliber" released almost 28 times the energy of the .50 BMG, with only a 27% mean loss in momentum. Energy, in most cases, is what is lethal to the target, not momentum. In conventional guns, muzzle velocity is determined by the quantity of the propellant (burn speed, expansion), the mass of the projectile, and the length of the barrel. A slower-burning propellant needs a longer barrel to burn completely, but can, on the other hand, use a heavier projectile. A faster-burning propellant may accelerate
Mass driver velocity would rather be around 62.75% of total mission delta v if operating at constant specific impulse, except greater optimization could come from varying exhaust velocity during the mission profile (as possible with some thruster types, including mass drivers and variable specific impulse magnetoplasma rockets). Since a mass driver could use any type of mass for reaction mass to move the spacecraft, a mass driver or some variation seems ideal for deep-space vehicles that scavenge reaction mass from found resources. One possible drawback of the mass driver is that it has the potential to send solid reaction mass travelling at