sentences:  The bore was rifled in order to increase the accuracy of the L21A1 plastic baton round, thus reducing the likelihood of unintentionally hitting a vulnerable part of the body and causing a fatal injury.Based on the HK69A1 is the HK79 underslung grenade launcher, designed to be mounted under the barrel of the G3 and G41 series of assault rifles (with the exception of the short, carbine versions).When attached, the HK79 does not affect the accuracy of the rifle, since the barrel is free to oscillate.