1: Obtain a Ti-83 series of calculator or download a simulator.
2: Download the SGBC from the theories/accessories forum. (I created a version for MirageOS!)
3: Using either GGDT or better yet, a chronograph, clock the muzzle velocity of your cannon.
4: Using the bubble level indicators found on level sticks, create a mount for your gun using protractors and sticks.
5: Using a compass, set the correct azimuth for the shot and using the SGBC, the angle.
6: Pray to god the mount doesn't break when you fire.
Viola! You just put a freaking potato downrange with greater theoretical accuracy than PVC should EVER be able to match. Good job.









