The weld interface is investigated between copper flyer plates and brass parent plates that are impact spot welded by the use of LDPE projectiles of various nose shapes. Projectiles with a flat nose featured plane and wavy interfaces with a central unwelded zone. In contrast, projectiles with conical noses did not display unwelded zones at the spot. Hollow ended projectiles featured shaped-charge effects, and generally resulted in welded regions comprising a central pocket, a concentric toroidal ring and concentric zones of wavy and plain regions at various radial distances. Cases involving entrapped air and jetting are observed.