Hi guys, I am hoping some one can help me out here and after some forumlas and very basic ones at that on internal ballistics. There is a heap of information out there and they tend to jump straight to the hard stuff which tends to be tough on a novice like myself. I have done a heap of googling and the formulas are either totally over my head or not what I am after. The formulas are based around ww2 tank guns, so caibres of 20mm up to 120mm I have some real world figures below, but cannot work out the relationship that can determine the muzzle velocity from the powder mass diameter=37mm shellweight=.600kg cartridgesize=145mm velocity=670m/s barrellength=37.7 calibre diameter=50mm shellweight=2.06kg cartridgesize=419mm velocity=835m/s barrellength=60 calibre diameter=75mm shellweight=6.8kg cartridgesize=495mm velocity=740m/s barrellength=43 calibre The formula I have come up with just does not cut it. I was using X as a pseudo factor to get the rough estimates so Force would equal Force. As you can see I am far from a physics genius and that why I need help. P = Volume of Powder X = Explosive force Factor m = shell mass v = velocity PX = mv^2 sqr (PX / m) = v Now I know there huge amount of factors that add and subtract but I am after even ballpark forumla based on powder being the same quality and power, shells the same aerodynamic velocity. What I am trying to achieve is if I know the powder volume and the shell weight and the calibre, what is the muzzle velocity Please remember to keep it simple and a example is always great, thanks for any help that can be given.