<p>An electromagnetic launcher’s inductance gradient is increased to boost the force on the projectile directly. Smoothing the rails’ outside surface is one way to improve the inductance gradient. Filleting is the process of smoothing the edges of rails. By maintaining the sliding contact intact, this research explores the impact of small radii on both sides of the rails in an augmented electromagnetic railgun. The two-sided filleting technique, known as the double filleting method, is the focus of this research. The study investigates the effects of double filleting on the rails with respect to the projectile’s kinetic energy, barrel efficiency, projectile force, and rail–armature contact forces. Different configurations of double fillet rails in augmented railguns are compared to traditional augmented railguns with cuboid shape rails in terms of performance. Dynamic field distributions are investigated using LS-DYNA models of specified railgun geometries. Subtle changes observed in the barrel efficiencies, muzzle velocities and contact forces of analyzed configurations are presented.</p>