OK, you're going to love this one. Somehow, it has to be possible to describe the overbore charactoristics of a cartridge and the inches of barrel required to burn the volume of powder it contains. For instance, I read an article some time ago where the author took an 8 x 57 with a 29" barrel, fired it over a chono, recorded the velocity, cut an inch off the barrel and repeated the process again. In the end, the 8 x 57 gained velocity with every shortening untill it got to about 22" or so and then it started to loose velocity. As I recall, it was around 18" when it had slowed to the same velocity that it started out with.
Somehow, there is a formula that states " when X volume of powder is burned in Y diameter bore with Z weight projectile in front of it then W length barrel is required to burn all of X powder without slowing the bullet due to excessive barrel length". This formula could also give an approximation of velocity decrease per inch of barrel removed.
Feel free to tell your friends at the local university about this one... I'm sure that for the right person, it's not that tough.
All it takes is One Good Shot!