Speer TMJ Handgun bullets are engineered to be the cleanest-shooting projectiles available for target practice and competition. Unlike traditional Full Metal Jacket (FMJ) bullets that leave the lead core exposed at the base, these projectiles utilize Uni-Cor technology to bond a seamless copper jacket around the entire core. This design virtually eliminates lead vaporization during firing, making it the premier choice for indoor range use where air quality is a priority. These 155-grain bullets are swaged twice to ensure a perfectly uniform heel and a consistent .400 diameter, providing the high-velocity accuracy and reliable feeding required for high-volume training in .40 S&W and 10mm platforms. Defensive Application Non-expanding TMJ bullets carry a high over-penetration risk and do not create large wound channels. They are not recommended for personal defense.