It used to be at avhistory.org but they have moved totally to CFS3. I've attached Machine Guns & Cannons.zip which has the 1% spreadsheet that I downloaded years ago. The setting at the end of the Gunstation line should be the weight of 1 round and 1 link. The airfile places this at the co-ordinates given in the middle of the Gunstation line. The Guns line provides the details about where the projectile leaves the plane (and where the flash appears) as well as the trajectory. A P40 site at http://staff.jccc.net/droberts/p40/p40a.html