20mm Airsoft Howitzer
Posted: Thu Mar 05, 2015 5:28 pm
Hey, guys! I just *finished* my first airgun! 
Okay, yeah, it's not my 'first' actually, but it's the first one that's been finished to operational standards, instead of just going to 'proof of concept' and no further. 
After building a small hammer valve for a project I'm working on (airsoft shotgun) I thought to myself, "Hey, I LIKE hammer valves!!" They're elegantly simple, remarkably efficient compared to ball valves, and much cheaper than QEVs. And they're easy to make. Since I had a couple of fire extinguishers lying around, I figured I'd make an airsoft heavy weapon for our frequent games. 8)
It started out as just the hammer valve and air tank, with no particular design intended. I was thinking about using it to make a shoulder mounted RPG type thing, but then I figured it might be more fun and more fair to build it into a heavy artillery weapon. And darned if it isn't just that!!!
I test fired it at %40 of the planned air pressure with a shotgun style sabot with around 25-50 BBs in it. Ended up with a six foot BB blast that went about 60 feet. Not massive range, but that's not the intent. At the full power (planned 100 PSI), it should be firing around 100-150 feet with a much bigger spread. Perfect for war games. 
What's that? You want pics? Okay, here's some to get ya started.
Frontal view to show off the blast shield and barrel.
Side view. You can see the bolt handle (bolt is inside the black 'firing' chamber) and the hammer (small green pipe and cap). The hammer springs are heavy enough to open the valve on their own, without the impetus of the hammer. The idea is to open the valve and keep it open, so all the air is used in a single shot. This was to increase power, but more importantly, to make it a single shot weapon. Gotta keep the game realistic. And fair. 
Pic with my little brother kneeling beside the gun, for size comparison. It's not huge, due to cost restraints. However, even if I had the money, I'd probably have kept it about this size, anyway. It already weighs abut 50-75 lbs, so anything bigger would be a PITA to move around and/or store after a game.
Okay, yeah, it's not my 'first' actually, but it's the first one that's been finished to operational standards, instead of just going to 'proof of concept' and no further. After building a small hammer valve for a project I'm working on (airsoft shotgun) I thought to myself, "Hey, I LIKE hammer valves!!" They're elegantly simple, remarkably efficient compared to ball valves, and much cheaper than QEVs. And they're easy to make. Since I had a couple of fire extinguishers lying around, I figured I'd make an airsoft heavy weapon for our frequent games. 8)
It started out as just the hammer valve and air tank, with no particular design intended. I was thinking about using it to make a shoulder mounted RPG type thing, but then I figured it might be more fun and more fair to build it into a heavy artillery weapon. And darned if it isn't just that!!!
I test fired it at %40 of the planned air pressure with a shotgun style sabot with around 25-50 BBs in it. Ended up with a six foot BB blast that went about 60 feet. Not massive range, but that's not the intent. At the full power (planned 100 PSI), it should be firing around 100-150 feet with a much bigger spread. Perfect for war games. What's that? You want pics? Okay, here's some to get ya started.
