 While mounting sandbags around a tank had little effect against high-velocity anti-tank gunfire it was thought to provide standoff protection against HEAT weapons, primarily the German "Panzerfaust" anti-tank grenade launcher and the bazooka-derived "Panzerschreck" 88 mm calibre anti-tank rocket launcher.In the only study known to have been done to test the use of sandbags, on March 9, 1945, officers of the 1st Armored Group tested standard "Panzerfaust" 60s against sandbagged M4s; shots against the side blew away the sandbags and still penetrated the side armor, whereas shots fired at an angle against the front plate blew away some of the sandbags but failed to penetrate the armor.Earlier, in the summer of 1944, General Patton, informed by his ordnance officers that sandbags were useless and that the machines' chassis suffered from the extra weight, had forbidden the use of sandbags.