Well, all I did was take the penetration formulas in 3G3 and did the algebra to derive the Silhouette conversion formula as per the 3G3 rules. I found that the number was 3.7, but it was rounded up to 4 in the book. So I just posted what I found on the DP9 boards. Honestly, I think it was rounded to 4 because the biggest criticism of the VCS was the mathiness of it--for determining TVs and costs, of course. Multiplying by 4 is easier than 3.7, sure.That was former Heavy Gear line editor Marc Vezina himself, as I recall. I used the 3G3 rules for the Equipment Catalog at his request, though I tweaked the formula a little for my purposes. (And you changed the stock formula from 4 to 3.7, by the way.)
Anyways, it was a hiccup that was easily corrected if you wanted to. In the end, at my table we decided to make the higher DM value 5mm and 7mm Paxton rounds analogues to the 5.56mm and 7.62mm NATO rounds. The 7mm rounds in the main rulebooks were 7.62mm Pact rounds, and that worked for us on many levels.