Mark made it clear that his formula was only an average, and my test results were certainly different.
The results I got included: max penetration only out to 10% range (instead of 20% range), and at max range I was only getting about 20 to 25% penetration (instead of 33% penetration).
I don't know what weapons Mark used to get his results, but it seems that results may vary quite widely depending on a number of factors; that may even include warhead size (Mark mentioned this) and crew experience.
I did a test that included accuracy (or caliber to barrel length ratio) and didn't find that made a difference.
I found that at close ranges the pen was more consistent, and at greater ranges you usually got one of two results. For example a gun may consistently pen 9 at 20% range, get 7s and 6s at 50% range, and at 60% range get 6s and 5s.
Then you get the occasional ‘wild card’ extra 1 or 2 pen; and you may also hit a ‘weak spot’ for an extra 1 pen.
My tests did show an approximate linear degrading of penetration from the range where you no longer get max penetration (10 to 20% range) to max range.
So theoretically, if you discover the range a weapon no longer achieves max pen, and the penetration a weapon achieves at max range, you should be able to come up with a formula to show approximate penetration at any range in between.
But that’s beyond my maths ability.
cheers,
Cross