Unlike conventional FMJ bullets that leave lead exposed at the base, Speer uses Uni-Cor technology to completely encase the TMJ bullets lead core in a seamless jacket. Its cleaner, more accurate and more consistent than any FMJ. Oal .598" Series TMJ Weight 180 gr Quantity 100 Per Box Cannelure No Bullet Type Total Metal Jacket Core Material Lead Bullet Caliber 40 Caliber Bullet Diameter .400 Jacket Material Copper Unit Of Measure box Recommended Usage Target Sectional Density .161