In spite of the benefits of the modern carbine, many armies are experiencing a certain backlash against the universal equipping of soldiers with carbines and lighter rifles in general, and are equipping selected soldiers, usually designated marksmen, with higher-powered rifles. Another problem comes from the loss of muzzle velocity caused by the shorter barrel, which when coupled with the typical small, lightweight bullets, causes effectiveness to be diminished; a 5.56mm gets its lethality from its high velocity, and when fired from the 14.5" M4 carbine, its power, penetration, and range are diminished. Thus, there has been a move towards adopting a slightly more powerful cartridge tailored for high performance from both long and short barrels. The U.S. has experimented with a new, slightly larger and heavier caliber such as the 6.5mm Grendel or 6.8mm Remington SPC, which are heavier and thus retain more effectiveness at lower muzzle velocities.