Controlled expansion at close range has been a core element of the Remington Core-Lokt design since 1939. Proven results from Core-Lokt ammunition have made it the world's best-selling hunting ammunition of all time. The Core-Lokt design has been tried and tested the world over with great success. Its time-proven performance has made it the world's best big game ammunition. The tapered copper jacket is locked to a solid lead core delivering massive twofold expansion, weight retention and consistent on-game results. Its time-proven performance has made it the world's best-selling hunting ammunition of all time.