Two problems with that: going up is only 3% of the energy that is required. The other 97% is "going fast enough sideways to stay up". The other problem, even if

Two problems with that: going up is only 3% of the energy that is required. The other 97% is "going fast enough sideways to stay up". The other problem, even if you angle your shot, is that you need to raise the perigee so that your orbit doesn't intersect the launch site anymore. These two things combined mean that you would have to railgun a rocket that is still about half the size of a rocket that takes of normally. And liquid filled rocket would NOT like or withstand a rail gun launch. But you have should bought yourself TWO major technological problems: rocketry and rail guns. That is not economical at all. Much easier to make the rocket a bit larger (you need to develop a rocket anyway) and get rid of the complexity introduced by the rail gun.