<b><font color="beige">Capt. Turner
The information you seek is located in the game help files, copied here.
<font color="green"><b>"Select <u>Quality Fire Modifiers </u>to have fire results be affected by the quality of the firing unit. Non-artillery units which have a quality of A or B will have a 10% modifier applied to their fire value. Non-artillery units which have a quality of E or F will have a 10% modifier subtracted from their fire value. See the Design Notes for an explanation of these modifiers."</b></font id="green">
The modifier is only 10% one way or the other, but the standard fire results can give a pretty wide range of results which could explain your <i>super units</i> fire results. Personally I like the standard fire results which can to be unpredictable, but by using the Optional Fire Results option (see below) in conjunction with the Quality Fire Modifier will result in more predictable averaged out losses.</font id="beige">
<font color="green">"If you select <u>Optional Fire Results</u>, then the resulting fire casualty values are based on the average of two default fire calculations. This produces values which are more likely to be in the midrange of the casualty interval rather than uniformly distributed." </font id="green"> </b>
<center><font color="blue"><b>Maj.Gen. R.A.Weir</b></font id="blue">
<font color="yellow">THE CALVERT LINE</font id="yellow">
<b>First--III--AoA CSA</b></center>