If this thread isn't dead... can anyone come up with a burn rate for a powder? Any powder really. I looked at the formula that was created by Powley but that assumes that the psi is a constant unless I have read it wrong. I am currently trying to write a program that does something very similar to the slide calculator mentioned for my engineering class but I have been running into roadblocks everywhere trying to calculate a crude muzzle velocity given the bullet weight, caliber, grain. Is this impossible? Any and all advice is greatly appreciated!!