Why is the spear in a railgun shorter than in a standard gun?
The support given by the rail allows the gun to use a shorter spear than a normal gun. To make a standard gun accurate, the length of spear has to be such that the section protruding from the muzzle will counter the sag in the middle section. This will be apparent when too short a spear is used, because it will shoot high. The opposite is true if too long a spear is used, as it will shoot low.
