Hey, was doing some research on topic of Gau-8 (relating to ground vehicles) and found this and wanted to chime in. Thought the conversation was interesting but it doesn't seem like the individuals discussing report actually read the report in detail. Don't mean to resurrect an old topic but you can find the actual study done back in 1979 here: http://www.dtic.mil/dtic/tr/fulltext/u2/a522397.pdf)
First these aren't T-62s these are M-47s used to simulate T-62s but that isn't the main issue at hand. Out of the potentially ~1300 rounds on board, per the test the pilot fired only 174 rounds at 10 M-47 targets (10 passes) or 13%. It only takes one perforation to to do significant damage. Take a look at Table A-I on page 40 of the report, of the 174 rounds fired at the 10 targets about 52% impacted a target, of those there was 30 perforations. I'd find it more likely that a modern A-10 pilot would fire many more rounds per tank vs modern tanks to increase probability of killing one. How confident would you feel to have an A-10 strafe you in a modern tank from side or rear and fire 175-200 rounds at you? Me not very... Keep in mind the fire related estimates were considered conservative since the target engines and systems were not running to circulate fuel and oil. (page7)
Seems like quite an effective back-up weapon to kill and disable tanks after the primary weapons have been expended (AGMs, cluster bombs).