A long time ago in a galaxy far a way, my best shooting buddy and I decided we could burn more powder and have more fun if we built ourselves a couple of cannons. Now this was in the early 1980s and Dangerous Dave, the Old Western Scrounger (Dave Cumberland) still had two muzzle sections from 3 inch .50 caliber naval guns salvaged from decommissioned Liberty Ships in stock. We bought the last two (6' long muzzle sections, rifled with a chrome bore 24 grooves, one turn in 96 inch twist). We proceeded to machine a breach and put trunnions one the first one. After some heavy math (I was extracting cube roots on a pocket calculator - not one with root functions) we came up with a projectile weight and a likely maximum charge of smokeless powder. We worked up to that and when we first fired it, we both took cover in a ditch while it went off.
Eventually we were sending 8 lb. lead projectiles down range at an estimated 1600+ fps. A solid hit would pick a '58 Plymouth up a food and set it back three. We did not shoot at close range. But by using the barrel as a peep sight, with the breech plug out, and estimating the hold-over from experience, I could hit a 2' diameter target with the first shot at 300 yards. It was some fun!
The biggest difficulty was building a carriage that would withstand the recoil - we broke everything we ever made to pieces, except the gun itself.
We were careful and never blew up the gun, and I am here to tell the tale. I have a spent projectile in my office that went through a 6' fir stump and slid 300 yards up a dirt road. Like I said it was some fun. The first time we took this monster to a cannon match, and ran after lighting the fuse for the first shot, was an event.
