With APCR (HVAP shot) rounds the US 76mm M1 was effective against the Panther at 900 yards, but not much beyond 1000 yards.
This is not true. This is from the book "M4 Sherman, Combat and Development History of the Sherman Tank and All Sherman Variants" " Sgt. Ross Figueroa of the 2nd AD stated in a report: This incident happened on March 2nd 1945, When I gave my gunner the order to fire at an enemy Mark V tank at the range of 1600 yards with first round which was APC and it bounced off. My second round was a HVAP which destroyed the Mark V and set it on fire." Figueroa went on in his report to describe another combat acton in Germany. "While on the right of the village of Fischein, Germany, I was placed in a firing position by the platoon leader. In my position I had a field of fire extending to a distance of 2000 yards, covering several roads. While in this position, I spotted a Mark V Panther moving across my front. For my first shot I used an APC, establishing my range, which was 1600 yards. The next round was an HVAP. It hit the tank, immediately setting it on fire. Later I had an opportunity to inspect the tank and upon seeing the size of the hole made by the projectile, I am confident in the shell and would like to have more of the ammunition. With such ammunition I wouldn't be afraid to shoot at any of the enemy vehicles, especially at ranges where our normal ammunition now ricochets off of the enemy armor."
Jag34