I thought we could make this post a compilation of commercial semi automatic mechanism. For the likes of the Evanix Viper, Hatsan Sortie and many more

I tried building a similar blowback gun, running at 200psi with green gas. Even with a port to the hammer tube, so having the air push on the bolt and the hammer, it still isnt strong enough to make the gun run automatically.
I might shelf this project and go back to semi auto stuff

Joerg Sprave did some airbows using these pipes. They hold the pressure, but i would still buy a paintballtank. Your safety is definitely worth more than the 80 bucks for a pcp bottle

How do the BBs get into the Barrel? Via a sliding magazine over the barrel?

Have you figured out how it works? It has to be extremely simple, given that the hardware kit he sells, has only very few parts.
Powerwise, you never see the gun when he fires, the video cuts every time he shoots. Seems a bit fishy, he is hiding something...

I use 0.2g 6mm Airsoft-BBs, i may post the firing video soon!

Finally my Semi-Auto Pistol project is finished to my liking. It runs on green gas (@12Bar) using a 2-stage trigger with a sliding hammer mechanism actuating the valve. It has NO BOLT, it is using a internal 11 shot magazine, that is sealed with the barrel. It has around 1.2J of muzzle energy and fe...

You may get away with no bolt at all. I have done that multiple times. Just seal the magazine with the barrel so that no air can escape. This makes the whole thing more powerful and simpler

Hi guys, i was wondering if there was a formula for the parameters(Barrellength and Projectileweight) for the most efficiency, not the most power. For the barrel length i figured the most effective would be that the barrel has the same volume as the volume of the released air (Volume of the Plenum)....

What i usually do is to drill a small deepening (about 2mm deep with a 5mm drill bit), the BBs get pushed in the Barrel and in the indentation so they cant roll out.

Ah, you made it :) Welcome to the forum! A lot more sophisticated design than I was expecting. I really like the double action trigger, very clever! I suppose the biggest disadvantage though is that it is not easily adjustable, so for example you could be dumping a lot more air per shot than is nec...

Hello guys, this is my first post and please excuse my english :) This is one of many attempts at building a selfcontained semi-automatic pistol with an autonomy of at least 20 shots. This pistol uses a double action trigger, when you pull the trigger it pushes the hammer back until it hits a "ramp/...