With the advent of smokeless powder, which has a far greater energy density than black powder, it was possible to generate far more power in the large cases of the older black-powder cartridges. Cartridges such as the .32-20 Winchester and .44-40 Winchester were chambered in both revolvers and lever action rifles, and the rifles' actions could handle much higher pressures. This led to "machine gun only" loads in these calibers, which provided far more velocity and energy in the rifles, but were not safe in the revolvers due to the higher pressures they generated. These loads were eventually dropped due to a combination of safety concerns, and new smokeless rifle cartridges that offered even higher velocities, such as the .30-30 Winchester.