Hollow cylindrical Al-6061 T6 projectiles, driven in a coilgun system, suffer radial compression and buckle into quadrilateral or pentagonal cross sections. In some cases, the projectiles fail by developing longitudinal cracks in the compressed region. Simulations of the coilgun-projectile system, using Johnson–Cook and Bao–Wierzbicki failure models, reproduce buckling and formation of longitudinal cracks via localization of plastic strain and high temperatures around the bends of the buckled geometry. Failed specimens were micro-graphically investigated and the cause of failure attributed to synergistic effect of buckled geometry and localized high temperature zones.