Semi-automatic copper airsoft gun

GalFisk · Posted: 01/01/2006 2:12 AM Post subject:

The semi airsoft gun, (almost) finished. It has a calculated chamber volume of 70 cc, and a barrel length of 90 cm. the barrel id is 6.4mm, so the fit isn't perfect, but it's good enough.

It shoots quite well, there are misfires now and then and two bbs are also loaded sometimes, but overall it's pretty reliable. I think the reason for multiple BBs being loaded is that the magazine gets slightly pressurized, which may push a bb into the barrel.

Both the trigger valve and hopper became physically bigger than I had expected (my fault for not trying to model them), but the balance and weight of the gun is nice and I don't find the size to be a problem. The hopper holds about 800 bbs, and the cap is airtight. I had originally intended to mount the trigger on the side of the gun and connect it with a hose, but this way works much better. The exhaust from the pilot hits my fingers when it's triggered, but it's not enough to be unpleasant even at 300 psi.

Since the valve and hopper both are in the way for aiming down the barrel, I plan on putting a laser pointer on the gun later. I don't expect it to be very accurate anyway though, since the BBs are a sloppy fit and the barrel is very slightly bent.

The hopper gave me the most trouble, I had to reattach it twice. Now it's attached with solder, two layers of jb weld and some enameled copper wire. I'm also being more careful not to stress it.

I have done many test shots on phone books wiht both light (0.20g) and heavy (0.87g steel) bbs, and it works well in both cases. An advantage is that the bbs can be picked out of the book and reused.

I'm going to get a paintball CO2 setup that will make the gun portable. I pln on running it at 300 psi, which GGDT predicts will give a velocity of about 240 m/s for the steel bbs.
More pics here: http://galfisk.kaaven.net/gallery/thumbnails.php?album=29