I challenge you to find me a legit source showing the penetration abilities of the T34/85mm HVAP surpassing that of the standard AP from an M4A3(W) 76mm at longer ranges. So far, I have not found one single chart that displays any advantage for the 85mm HVAP beyond (actually somewhere prior to) 1000m, or 1094 yards, and up close (500m) the advantage is hardly worth mentioning compared to the 76mm AP of the M4A3. The HVAP round really shows its advantage at less than 500m vs the standard 85mm AP, the HVAP gains 30mm more armor penetration at 100m, and the advantage slowly declines until around 800 yards, Im guessing. The gaps in all the charts I've read are too big to show the exact cross over from advantage to disadvantage for the HVAP.
One online source shows the following stats for armor penetration:
M4A3 76mm AP: 500m = 104mm; 1000m = 83mm; 1500m = 67mm; 2000m = 54mm
T34/85mm HVAP: 500m = 107mm; 1000m = 76mm; 1500m = 54mm; 2000m = 39mm
T34/85mm AP: 500m = 100mm; 1000m = 81mm; 1500m = 71mm; 2000m = 65mm
Now compare the Tiger's armor to those ranges and you'll see that the T34/85mm's gun is no better off vs a Tiger, unless almost point blank range with HVAP, compared to the M4A3(W) 76mm's AP.
As far as the T34/85mm being a "better" tank, that is matter of opinion in every which way but loose. The quick reload times of the M4A3 is not to be over-looked, like-wise, the speed of the T34x is an often over-looked attribute. Roll the dice, and play the yardage. The T34's frontal armor will be its ultimate saving grace in a stand off pot shot battle. To me, comparing the effectiveness of the penetration capabilities is a moot point, they are too similar. It is the other attributes of the tank that will stand out instead based on what the role is that is needed to be filled and/or the mission that needs to be accomplished.
FWIW, it is one of those two tanks that I take %90 of the time in the MA. 
Stumbled on a thread in another forums that was having a debate similiar to this and someone in that thread posted the results of some testing the Yugoslav army did after the war comparing the T-35/85 with the M4A3(76). Basically, when comparing HVAR between the two tanks the Yugoslavs found that:
- HVAR rounds fired from the 76mm M1A1 was 10% more accurate than the ZiS-S-53 gun up to 1000meters and accuracy the same up to 1,500 meters
- Both HVAP rounds showed poor performance at ranges of 1,500 meters
On AP rounds:
- Accuracy the same up to 1,500 meters
- at ranges from 1,500 meters to 2,500 meters (maximum effective range firing AP rounds for both guns), the ZiS-S-53 was 20% more accurate
On He rounds:
- Accuracy the same up to 1,500 meters
- at ranges from 1,500 meters to 3,000 meters (maximum effective range firing HE rounds for both guns), the ZiS-S-53 was 20% more accurate
Gunsights were judged to be about the same, though the T-34/85 was credited with having a marginally better gunsight but the differences were judged to be insignificant.
Views were better in the Sherman but over all both tanks were considered poor.
Firing from the move was judged to be very poor for both tanks, with the Sherman being marginally superior in firing from a short halt.
In comparisons between guns, the ZiS-S-53 was judged to have better penetration than the M1A1 76mm but the difference was considered to be marginal.
all in all, seems like the T-84/85 and the M4A3(76) are relatively evenly matched.
Found some data on another forum comparing HVAR rounds for both tanks.
Russian 85mm HVAP
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Fired at 1040 m/s
0.65 kg tungsten core
27.94mm core diameter in American analysis, 27.77mm from Russian data.
100m, 1009 m/s, 165mm vertical target penetration
300m, 947 m/s, 150mm
500m, 887 m/s, 137mm
1000m, 744 m/s, 107mm
1500m, 614 m/s, 81mm
American 76mm HVAP
==================
Fired at 1037 m/s
1.765 kg tungsten core
38.1mm core diameter
100m, 1018 m/s, 240mm vertical target penetration
300m, 981 m/s, 226mm
500m, 939 m/s, 211mm
1000m, 848 m/s, 179mm
1500m, 756 m/s 149mm
In some tests conducted by the Soviets comparing the U.S. 76mm APCBC round to the Soviet 85mm APBC round in trials against a captured Tiger II found that the US round was significantly better in penetrating the Tiger II.
Comparing Russian 85mm HVAP to 85mm APBC against vertical targets results in:
100m: 165mm for HVAP, 139mm for APBC
500m: 137mm for HVAP, 123mm for APBC
1000m: 107mm for HVAP, 105mm for APBC
1500m: 81mm for HVAP, 91mm for APBC
For U.S. 76mm APCBC:
100m: 239mm for HVAP, 125mm for APCBC
500m: 208mm for HVAP, 116mm for APCBC
1000m: 175mm for HVAP, 106mm for APCBC
1500m: 147mm for HVAP, 97mm for APCBC
Sourceack-ack
