I did a Google search on "M1 Abrams Turret" and could find nothing about any flaws. However, I did find this:
History - Gulf War
M1 Abrams Main Battle Tank
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The following story happened to an M1 Abrams main battle tank in General Barry McCaffrey's 24th Mechanized Infantry Division during the Gulf War.
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It was raining heavily, and one M1 managed to get stuck in a mud hole and could not be extracted. With the rest of their unit moving on, the crew of the stuck tank waited for a recovery vehicle to pull them out.
Suddenly, as they were waiting, three Iraqi T-72 tanks came over a hill and charged the mud-bogged tank. One T-72 fired a high-explosive anti-tank (HEAT) round that hit the frontal turret armor of the M1, but did no damage. At this point, the crew of the M1, though still stuck, fired a 120mm armor-piercing round at the attacking tank. The round penetrated the T-72s turret, blowing it off into the air. By this time, the second T-72 also fired a HEAT round at the M1. That also hit the front of the turret, and did no damage. The M1 immediately dispatched this T-72 with another 120mm round. After that the third and now last T-72 fired a 125mm armor-piercing round at the M1 from a range of 400 meters. This only grooved the front armor plate. Seeing that continued action did not have much of a future, the crew of the last T-72 decided to run for cover. Spying a nearby sand berm, the Iraqis darted behind it, thinking they would be safe their. Back in the M1, the crew saw through their Thermal Imaging Sight the hot plume of the T-72's engine exhaust spewing up from behind the berm. Aiming carefully the M1's crew fired a third 120mm round through the berm, into the tank, destroying it.
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The above story copied from "Armored Cav - A Guided Tour of an Armored Cavalry Regiment" by Tom Clancy. Visit the Tom Clancy home page.
M1 Abrams