In 1993, FBI and BATFE agents used armored vehicles and tanks and attack helicopters during the siege of the Branch Davidian community in Waco, Texas. The FBI's arms included .50 caliber (12.7 mm) rifles and M728 Combat Engineer Vehicles, which are based on an M60A1 Patton main battle tank chassis. The FBI also launched CS grenade fire from M79 grenade launchers and fired two military M651 rounds at the Branch Davidian site. 40mm munitions recovered by the Texas Ranger Division at Waco included dozens of plastic Ferret Model SGA-400 Liquid CS rounds, two metal M651 military pyrotechnic tear gas rounds, two metal NICO Pyrotechnik Sound &amp; Flash grenades, and parachute illumination flares. The Army Tech Manual for the M651 warns that it can penetrate -inch plywood at 200 meters and the "projectile may explode upon target impact".