Description Sierra Bullets has partnered with SIG Sauer to bring you the ultimate defense bullet line delivering optimal weight retention and expansion at all effective distances combined with Sierra’s world renowned accuracy. The line features a stacked hollow point bullet design with additional hollow point cavity. For the #9924 #9925 #9465 and #9820 a cannelure halfway up the shank locks the jacket to the core ensuring maximum weight retention and terminal expansion. The #9924 was introduced in November 2015.