20 pounder vs. T54's front hull

[Aeraaa]

Oh, and here's another link that mentions what I've said: http://www.dtic.mil/dtic/tr/fulltext/u2/a954868.pdf

On page 6 it says: "Since the HEAT shell does follow the cosine law, a round which can penetrate a 12 inch plate at normal obliquity, can defeat a 6 inch plate inclined at 60deg obliquity. For comparison, the 90mm HVAP M304 shot can defeat 12 inch plate at 0deg obliquity, at ranges up to approximately 1300 yards, but cannot defeat even 4 inch thick plate at 60deg obliquity when fired at point blank range."

Unfortunately, finding a link like that for 20 pounder ammunition is proving extremely difficult. Nonetheless, I do believe that 20 pounder will have trouble defeating T54 hull armor above 400 meters at best.