Russian Tank Gun Accuracy

1. There is quite a bit of misunderstanding on various game sites as to the accuracy of WWII Soviet guns.  This comes about by comparing the dispersion numbers from the Soviet firing tables to the German 50% zone dispersion numbers.  The Soviet values represent the median deviation of the guns. This is equivalent to probable error (w) in the table below.   To compute the 50% dispersion zone  (2w) from the mean dispersion values multiply by 2. 

for 'Mean Deviation'. I had the 50% zone as 1.69  times the firing table deviation data.  I have revised that to 2 times the firing table deviation data.

2. The following is a remake of the Russian 122mm D-25 firing table.  Unfortunately I don't have a date for this.  It is not a WWII table as the Russians 122mm ballistics were incorrect in 1944.  The German 88mm/L71 firing table is to the right so it can be compared.

* from Rheinmetall Weaponry Handbook 1982
Or here   
Video of Mean to Standard Deviation
Conversions link

4. Below is a compilation of the 122mm Firing table made from official 1960 D-25T DDR data and 1972 US 'Protection' criteria 122mm A-19 chart. (BTW I obtained the last source from Lorrin Bird so blame him for making notes on the data.)   

Note - Penetration numbers in parenthesis are computed and are not part of the original data.
Note - The dispersion data in table 3 and table 4 is the mean dispersion not 50% dispersion.
Here is a link to a PDF showing a comparison of US Protection Criterion penetration and Soviet CP penetration criterion.