Reminds me that during Desert Storm we were getting kills on HD T-72's through their hull front glacius plate at ~2000m even though they were behind a 3-4m thick berm from our M1's 120mm. I'm not sure about the efficiency of the Marine's M60A3's 105mm, but I had heard they were getting kills at out to 3000m (not sure if vs HD or vs frontal armor). BTW the "Brad's" chain-gun was taking out T-54/55's with little difficulty as well.