I thought this was wrong and an error on Shrapnel part, and now I know it is. You can buy sturmpioneers that run around with 32cm rockets with no reduction in speed which is BS, in fact these rockets were carried by either modified PzI or HTs, unloaded and fired:
I'm not familiar with Steel Panthers but if they are infantry maybe they merely carry a radio to direct the fire. If they are a vehicle then the idea that they would enter a battle area with their rockets pre loaded in the racks doesn't seem out of the question. though I would definitely say they are more vulnerable to fire and should not be allowed to reload their 6 rockets in the battlefield. See Pictures
https://www.tamiyausa.com/product/item.p...t-id=32566
http://www.axishistory.com/index.php?id=1297