Tungsten heavy alloys (WHAs) are high density materials widely used in ballistic applications because of their superior mechanical strength and high impact resistance. In this study, the perforation behavior of tungsten heavy alloy flat nosed projectiles with a W90–Ni7–Fe3 composition, manufactured via powder metallurgy, was investigated through combined experimental and numerical approaches. Flat nosed projectiles with specified dimensions (5.8 mm in diameter and 6.7 mm in length) were launched toward St37 steel targets with thicknesses of 1.5 mm and 3 mm at a controlled impact velocity of 260 m/s. Ballistic experiments were performed using a gas gun system to measure the projectile residual velocity and the Maximum back face deflection (BFD). Experimental results indicated that complete perforation did not occur for the 3 mm thin target and Maximum back face deflection was 5 mm. In contrast, complete perforation accompanied by plug formation was observed for the 1.5 mm thick target, with residual projectile velocities ranging from 123 to 135 m/s. Numerical simulations of the perforation process were performed using the LS DYNA finite element code. The Johnson–Cook constitutive and failure models were employed to describe the material behavior of both the projectile and the target. The numerical simulations accurately reproduced the projectile deformation mechanisms and the corresponding failure modes of the target, including plug formation. The numerical simulations showed consistent agreement with the experimental observations.