An M67 fragmentation grenade explodes on Range 111 during Back in the Saddle training aboard Marine Corps Base Camp Pendleton, Calif., Jan. 7. Marines with Marine Wing Communications Squadron (MWCS) 38 threw these grenades and also shot other weapons systems during the training. - An M67 fragmentation grenade explodes on Range 111 during Back in the Saddle training aboard Marine Corps Base Camp Pendleton, Calif., Jan. 7. Marines with Marine Wing Communications Squadron (MWCS) 38 threw these grenades and also shot other weapons systems during the training.