The Soviet T-28 tank

I have long been interested in the Soviet T-28 tank. With a 76.2mm gun, I would have thought that this should have been effective against many of the weaker German tanks. In the one book that I bought yesterday that covers the T-28, there is a photograph of a T-28 Model 1938 with an L-10 76.2mm gun that had a higher muzzle velocity. The L-10 was a 76.2mm L/26 gun. Wikipedia has a nice photo of a Finnish T-28, captured from the Soviet army. The Finns used seven T-28s until 1944. This Finnish page has specifications beyond what I have seen before, including armour penetration data from the shorter and longer guns. This page has a nice rear view of the T-28. This T-28 seems to have an advanced state of rust.