There are certainly entries in British war diaries of German tanks being destroyed by single first-hit rounds of APDS. Maybe they aimed 100 yards to the side of the target and got lucky. Seriously though, as with much else, the contemporary evidence over 17 pdr APDS accuracy is quite contradictory. Chris C mentioned above the issue of the APDS leaving deposits at the breech end of the barrel rifling and this would accelerate barrel wear, and promote inaccuracy even when firing APCBC. This would be another reason to restrict its use in combat. I'm not sure of the wear rate on the 17 pounder, but I do know that for the 20 pdr on the Centurion, it was inititally estimated that EFC barrel life firing APDS was 120 rounds, this eventually being reduced to around 60 after real-world experience. It was also estimated that 2000 HE rounds would have to be fired to cause equivalent barrel wear, so you can see that firing APDS had quite serious technical ramifications. What I think was overlooked at the time was that APDS should not really have been an interchangeable round with APCBC - it really was a different kind of weapon, and needed to be thought of very differently. i.e. it probably needed to be fired from a new barrel, should never have been fired speculatively, and would have necessitated far more frequent barrel changes. It would have also needed much more crew attention with regard to barrel cleaning in order to remove debris. So one of the faults in British thinking was probably that APDS was a simple solution to the Tiger/Panther problem, when in fact it necessitated a whole new operational paradigm. I should also note that for the 20 pdr Centurion, APDS was the only anti-tank round provided, with no APCBC, so the British had obviously learnt that particular lesson by 1950.