Semi Auto help!!? ( now works!!) PICS UP on page 2

[jackssmirkingrevenge]

Well this has allways been a problem for me all these years making BB guns= ive never been able to get hold of suitable tube for a specific ammo size that fitted perfectly with no blowby....

Have a look round ebay or your local hobby store, I'm sure you can easily find tubing with a 9mm internal diameter. Either that or have your magazine section drilled out of a block like SubsonicSpud is doing with his breech.

[psycix]

RC hobby stores carry it.
But why use that ammo if you can't find the right barrel for it?

Dont place the detent *that* far back. Just a liiiitle bit.
Airtightness should indeed help a lot already.

[django]

AHARHHHHH!, It now works!= after over 2 years of trying to get a Semi Auto to work I now have done it with thanks to guys on this site. I kept fiddling with the gun and turns out the Spring was too strong on the BB Plunger and pushing the second round out the barrel upon firing.

I took the Spring off then placed 3 ring magnets( not the strongest though) right before the Ball Detent and it now works perfectly!.Its not the most powerful at the moment as the barrel is only 19" Long because of the original length I had to work with and my previous mistakes with the gun and the .Also when it fires the air is having to fill up where the bbs are(dead Space) as theres no bb plunger and still that small gap around the bbs as the bbs are 9mm and barrel/mag 9.5mm.

I tried to locate 9mm ID barrel last week at numerous places but no luck, I cant even find any more of the Aluminium Tube I used on this one!.I guess I just set out to make a working Semi Auto Airgun for fun anyways which ive done,I'll be making the Barrel Longer and somehow encasing it in a frame but dont know what matterial I'll use, wood?.

Pics up later today.............

[django]

Still no pics,Sorry guys+camera probs= Last night I took all the last gun apart and bought some more aluminium tube and made a longer barrel version( the barrels 32" long!) I think I'll have to cut back the barrel a little as the guns just too big. I like to keep my guns a reasonably small size so it's easier to hide them because of our rediculous Aussie laws .

Anyways I am VERY pleased with the power of this thing, ive been shooting old video Cassette Tapes with it and it just destroys them sending erupting plastic all over the room and this is only at 110 psi.Min you its only at a distance of 5 meters( my back room with suitable backstop of course). I found out today that the 9mm BB's cost 20 cents each!! or if I buy 1000 they are 15 cents each but thats $150.00!,I was going to scrap the gun and go to a smaller 6mm version but the destructive power of the 9mm version is fantastic 8) .

I want to encase the gun in a gun shell but undecided what to use?,It'll be hollowed out so the gun can fit between 2 sandwiched peices that are screwed together so I can get access to the internals for repairs if need be. Was going to go with just wood but some sort of thick plastic sheet would be ideal, if I can find something like that?.............

[django]

Here we are, not much to look at yet as its not finished and housed in a shell yet but anyways.............

I Did away with the Spring/Piston( double feeding)








This was the gun with the barrel at 19"( currently 32", bit too long now)

[jackssmirkingrevenge]

yeah yeah, you don't just post pics with semi-auto, where's the videos?

Also, do you plan on higher pressures? If not, I think you need a bigger chamber for better performance.

[django]

yeah yeah, you don't just post pics with semi-auto, where's the videos?

Also, do you plan on higher pressures? If not, I think you need a bigger chamber for better performance.

Yeh Im trying to get Video Footage done mate, I dont know pressure wise, I'll probably go only 150 psi as I think thats all the QEV and Poppet are rated to.I have to charge up my 20 oz co2 so I can run higher than the 110 psi from my compressor .

I have no gauge on my Smart Parts co2 regulator either, ages ago for some reason I wrecked 2 gauges when using my strafers and it wasnt turned up very high at all( 120 psi or so).Took the Reg apart and could see no problem, its the low pressure(300 psi reg) gauges were the right ones too but just the spring wound type not liquid filled. So ive been using the reg turned down a bit,I think im going to make the chamber a little bigger anyways.

I plan on housing it all in a shell and will be bullpup style to cut down size,the mag cap will be at the back of the stock and will have to move the Poppet Valve much more forwards to where I'll put the Grip.
If I run an airline from the QEV to the Poppet Valve in a more forwards position will this affect performance??

[jackssmirkingrevenge]

Sorry if it didn't come across before but kudos for making it work, I know how long you've been working on this idea and trust me, I fully understand the glee at a glimmer of win after boatloads of fail

With 9mm calibre I think you can get away with 150 psi for decent performance, but why not keep the poppet valve where it is and just run a rod from the forward grip to the poppet?

[POLAND_SPUD]

i think that or this caliber there is no point in making a tube magazine... what you need is a hopper..

where did you get those fittings they look great

[django]

Today im trying to make a wood shell/stock for this gun but finding it hard to mark out and not look idiotic!, because of the dimensions of the gun so far its making it difficult. I mean im tying to encase this gun in 2 halves of wood and the distance between the steel puttied part (where the ball detent) is and the bottom of the poppet valve is 170mm so the body will be really wide and weird looking as its so wide.

If I move the Poppet valve forwards to where the grip will be( via airhose + barbs) i'tll reduce that width a little but if I do Im guessing performance will drop?.

[POLAND_SPUD]

ohhh sorry I though it's a full auto... that was why I wrote that the mag was too small...

but still I think that oyu can make it more egronomic if you move the mag tube in a different place... or switch to hopper for more ammo - maybe it's just me but I wouldn't like to relode every 8 rounds

you could also activate teh poppet valve via a wire or something like that so that it could stay where it is now but the trigger will be placed elsewhere

..or you can buy a solenoid spoolvalve and then just add a switch

[django]

Still working on this gun!,Its taking forever to make the Stock/Frame (from wood) anyways I found a strange problem with the gun tonight.If I have it firing at 110 psi it will double feed if I put in more than 6 rounds!,when I ran it at 90psi I will take 7 rounds before double feeding?.It only affects the first shot for some odd reason too,was hoping to run 150 psi through this but at that rate will only accept 3-4 rounds I suspect.

Im running that ball detent still and also a Rare Earth Magnet,but pretty sure it still did this before the magnet was onboard,will try dig out the magnet from the steel putty tomorrow to be sure.one other prob I can forsee is the steel bb detent wearing away the hole it pokes through as the tube is only alumimium tube(about 1.5mm thick)............

[django]

Guys I need some HELP!,right tonight I found out my poppet valve im using to actuate my 1/4" Qev Valve can handle 300 psi 8) http://www.clippard.com/store/display_d ... sku=MJVO-3

But I have no idea how much pressure 1/4" Qev Valves can handle safely?,I bought the Qev years ago so no idea on brand of Qev etc. Geeze this semi at 300 psi would be super but from memory QEV's can only handle 150 psi, correct?............

I fixed the feeding prob, the Rare Earth magnets too strong and causing double feeds so Ive altered it again, shooting tonight, after the compressor was down to 90 psi the 9mm bbs were going through a cardboard box,through a tough car matt made of carpet and rubber on the back of them,through a 4 times folded thick blanket then sticking in the foam behind the folded blanket . Still working on trying to gett footage up

[psycix]

I use my QEV's at 450psi.
They usually can handle more then their rating.
Make sure to test em though, if they can't, they will become a burst disk. Piston is replacable.

[django]

Still working on the stock/frame on this gun!,will finish carving out the stock tomorrow but looking at making a telescoping stock similar to what was available for the Ruger 10/22 rifles in the U.S years ago but dont know how the hell im going to do it?.

I mean I dont know what sort of catch to use to lock the stock still when at the desired position?,tried googling for ideas on such stocvk mechanisms but no luck?.also as the frame is only Pine Wood I wanted to use a lacquer on the wood and then paint it but unsure if the paint will stick ok to the lacquered surface?...............