Speer TMJ handgun bullets represent the highest evolution of the full metal jacket bullet. Uni-Cor® technology bonds the jacket to the core for terrific uniformity, and eliminates the opening found on the base of "other" FMJ bullets. This means reduced airborne lead because the lead core is encapsulated in copper. No trick "base covers" — our jackets are one-piece. Conventional FMJ bases can deform under pressure, and that hurts accuracy — TMJs won't let this happen.