Semi-completed Semi-Auto shell gun

[From_Hamsterdam]

This is my gun it works so far i only have to make/fix the firing system to get it to work fully.

It can hold about 7 shells in the mag. The mag has 2 sprinkler springs that. also eject the used shells.
i have currently only tested it up to about 90 psi because i brought the wrong pipe for the chamber and there are a few leaks.

The loading and extracting of the shells in entirely my design. Feel free to use it as long as you don't clame it as your own.



Bolt green
Shells yellow
Barrel blue
probe purple





The valve (not pictured) has just been triggered the air can not get past the probe (purple outline) so the bolt is pushed forwards.




When the bolt moves past a certain point the air can pass the probe (purple) and fire the bullet.




Now the air pressure has been released from behind the bolt it is pulled back by a spring or elastic bands. The screw is were the rubber bands attach to.



The bolt moves back allowing the next shell to move up.



As this happens the next shell pushes the old shell out. The light blue square represents the next shell. the old shell is ejected out of the gun just shown like this in the pick to give a better idea of how it works.


I need to make some way of firing more then one shot from one fill. Might buy a compressor or make a home made regulator. I also need to make a bigger firing chamber the current one is too small.



A= 25mm sh40 pipe (some low class stuff, class 8 I think)
B= 20mm sh40 with a slit in the side pushed over a 20mm pipe
C= 20mm sh40
D= 20mm 40sh pipe sleeved in to 20mm pipe
not shown 15mm electrical condute (white) barrel also used for shells

Offtopic
Yay, i have just completed my tafe course i now have a Diploma of engineering in computer aided drafting . Not a bad qualification for a 1 year course (took me 1 and a half) that cost me just over 2 grand

Edit:
wow those pics are big should i post links instead?

[jrrdw]

Congratulations on the gun and school. Gun sounds cool but i didn't notice what is pulling the spent shell out of the chamber??? The black back ground makes it hard for me to see details.

[jackssmirkingrevenge]

but i didn't notice what is pulling the spent shell out of the chamber???

The mag has 2 sprinkler springs that. also eject the used shells.

[lukemc]

WOW.... i like it. i doesn't look like a barrel of roses but it works and that counts for everything.

[judgment_arms]

Nice, looks like there’s another entrant in the arms race.
Looks like I need to get on the ball, between this and jack’s gun (you are still working on that right?) I’ve got a run for my money!

[jackssmirkingrevenge]

jack’s gun (you are still working on that right?) I’ve got a run for my money!

My second attempt at making the cartridge work failed so i've shelved it for now, I´m busy with work and the lady at the moment plus I'll be going abroad for work for most of July so don't expect and progress any time soon.

[spud yeti]

Nice gun! I like how the loading is original. Rapid fire if it turned into semi auto could look really cool with the used shells flying out!! I might not have seen you write it, but what are your ideas for a valve to use?? Maybe later a full gun picture... Im curious!
Great work though
Peace

[origin unknown]

Nice simple design which looks really reliable. Maybe you can make a video of it in action, if you get a compressor.

[turbohacker]

Awesome cannon!
I first of all, would like to congratulate you on making a semi auto in the first place. (it is a rare achievement!). I would like to further congratulate you on making one out of such ghetto parts! (no offence, ghetto's are probably cooler anyways because they cost so little and require more ingenuity to build). It is a very ingenious gun, I love it!
-END RAMBLING-

[From_Hamsterdam]

Gun sounds cool but i didn't notice what is pulling the spent shell out of the chamber??? The black back ground makes it hard for me to see details.

the next shell pushes the old shell out see second last pic.

sorry about the back ground i copied it from AutoCAD

My second attempt at making the cartridge work failed so i've shelved it for now

i will try post some picks of my 2 failed ones they are so bad, i even made one out of wood almost made my tradey friend cry when he saw it.
i love this gun simple cheap shells (50mm pieces of electrical condute). the bolt only has to move 1/2 the distance of the shell. the entire semi mechanism is only about 15mm long.

but what are your ideas for a valve to use?? Maybe later a full gun picture... Im curious!

i am currently using a modded sprinkler valve, my first modded sprinkler valve, so very leaky. the pic of the full gun did not work out it was so blurry you coudn't tell what it was.

Gotta be so proud

[Flying_Salt]

Sandpaper is your friend.

Nice job. I can see you making really creative piston valves and stuff.

[From_Hamsterdam]

full gun pic


ok i found a pic that worked. the chamber at the back needs to be bigger so it will work at lower pressure. if you look carefully you can see the elastic band connected to the bolt.

Sand paper is my mortal ENEMY!! i hate sand paper, it takes so long to get the job done, is always clogged up with glue and putty even when i haven't used glue or putty, the sand always comes off and i often end up with no skin on my knuckles for some strange reason . Now i need to go and shoot some thing.

[spud yeti]

Haha, I also use elastic bands sometimes, problem is that they break. I now try use springs instead, but they cost money! (duh)
Try find a flat file, I use them and they rule because they work fast, dont wear away and you never get your hands!
Why not try increase the chamber by using a bigger size PVC? (it should fit under there?)
Otherwise I really like the overall look of it

[From_Hamsterdam]

Why not try increase the chamber by using a bigger size PVC?

. Of corse i would use bigger pipe mainly because it is bigger!

i had 2 elastic bands so that is what i used.

[Solar]

Are you in the U.S. or from Hamsterdam?

I could offer some parts in trade if you would be willing to build one of your semis to fire my 40mm rounds. I have pressure chambers and shells ready to go.