Don't remember exact age or date but it was pre-12 years old and probably about 10 years old - late 40's.
I built my first gun. Found a .22 rifle barrell that someone was using for a tomato plant stake. It was old and rusty, and probably no one even knew what it was. I cleaned it up and chopped it into pieces about 3" long. Rifling was still reasonably good.
Took sections of that barrell and put them in pieces of iron pipe. They didn't fit, so I melted some lead and poured it into the gap between the pipe and barrell. Next came a connector with a plug inserted into one end. The plug was drilled and the firing pin went into the hole in the plug. The connector then went onto the pipe that held the barrell. All that remained was hitting the firing pin and driving it through the plug and onto the cartridge.
To accomplish this I got another piece of pipe. All this was about 3/4", I think. May have been a full inch. The second piece of pipe went into the connector so that the lug end of the pipe plug went inside the newly installed pipe. A cap on the remaining end, a hugh nail with a spring went inside the back pipe. Pull the big nail (it extended through the cap), release it and that nail hit the firing pin.
BAM! It's a wonder it didn't blow up in my hand, but it didn't. The way I shot it was to wrap my arms around a tree so that the tree was between me and the "gun" just in case it did blow up. It was a little inconvenient for self protection. Had to find a tree that was in just the right place. [img]/wwwthreads_images/icons/laugh.gif[/img] Also a bit hard to aim that way too. [img]/wwwthreads_images/icons/tongue.gif[/img]
This gun came after my first projectile launcher. A fire cracker gun. Short piece of pipe with a cap on the end. Cap has a small hole drilled in it. Put a firecracker in the end with the fuse through the hole in the cap. A glass marble, some paper stuffing, light the fuse, and wait for it to shoot. At least with the .22 I didn't have to wait.