Speer TMJs use Uni-Cor technology to take full metal jacket bullets to their highest level of evolution by completely encasing the lead core in a seamless jacket. TMJs won't foul ported recoil compensators like open-base bullets do. Speer swages each bullet twice, ensuring consistent diameters and a uniform heel. TMJ bullets are great for casual practice and plinking because, in addition to being super-accurate, they are economical.