semiauto MK III - vids

[POLAND_SPUD]

This is the 3rd version of my semiauto pneumatic

It operates exactly like MK I and MK II:
The air cylinder is hooked up to the chamber and it extended when the chamebr is pressurised. When you pull the trigger (actuate the 3 way valve) the QEV fires and the cylinder retracts and takes one round from the magazine and loads it as soon as the trigger is depressed. That's basically the whole cycle

This version uses 8.731 mm steel BBs as ammo as they are relatively cheap when compared with, for example 12.7mm steel BBs

The best thing introduced in this version this gun is the aluminium block/T that psycix machined for me. I really consider this to be a great leap forward as far as reliability and compactness are concerned

barrel - 100 cm 9mm ID hydraulic tubing
chamber - 20cm X 3/4" galvanised malleable iron + miscellaneous fittings
main valve - 1/2" QEV
pilot valve - mechanically actuated 3 way valve (bosch rexroth 0820402002 linky
the spool and the housing are so precisely machined they create a perfect seal with lubricated air)
scope - cheapo 4X20

total mass of the gun (with a vertical grip scope, mag and a 1/8" QEV to assist piloting) - 2.8kg


Right now it has a gravity fed mag/hopper (not included in these pics). I've ordered a suitable spring but it hasn't arrived yet

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I'd make more vids but the weather is really bad this winter

EDIT
I uploaded the 3rd vid again (IDK why but once uploaded on youtube it combined that two firsts shots into one so it sounded like a double fed or something)

[Demon]

This is the sniper i always wanted

I loved when the can falled off and you were still shooting it

Could you post a schematic please? I am not sure to understand how exactly it works. Where is the magasine ?

[Mr.Sandman]

This is the sniper i always wanted

I loved when the can falled off and you were still shooting it

Basically on par with how much Jsr hates seeing feet in pictures, please refrain from saying "sniper" when you mean sniper rifle. A sniper is a person not a rifle. By the way i think you mean fell . Ok, now that my grammar Nazi rant is over, I would like say that this version is much more aesthetically pleasing.

For some odd reason, I cant stand seeing wires on cannons, and you have done a great job on that. I do have a few questions though. have you considered porting the barrel to help with accuracy? It seems as though this gun is very accurate, but not to its full potential. Also, how fast does this normally shoot in terms of fps? I was thinking about modifying it and tweaking it a bit to accept a nerf dart for the nerf contest.

[Demon]

Is the gun using an external air supply or the steel pipe contains all the air pressure required for semi-auto shooting?

[psycix]

Wow where did you get that neatly machined block to house the loading system?
Oh wait I remember....


Anyways: nicely done Poland, this loading mechanism seems very reliable and I'm sure you will inspire other people to use it as well.


BTW: it looks like you posted this in the combustion cannon showcase... a mod will need to move it.

[Brian the brain]

All you need to do now is swing the chamber around and elevate the sight.

A rod could press the trigger, or perhaps a handbrake off a bike could be used to provide handle, trigger and remote line to operate it..

Well...just my thoughts..

I love the full barrel length silencer.

[Mr.Sandman]

love the full barrel length silencer.

By the way, I have been trying to find the video that you posted a few months back, it was in dutch and showed how to make silencers on a lathe. If you could "appear" it for me that would be great.

@demon I believe he uses a fridge compressor connected to the air chamber to supply continuous pressure, I could be wrong though.

[velocity3x]

@Poland,
Very cleaver design. The one thing pneumatics have an overabundance of is air and you're using it to reduce your work (loading). I'm a fan of automation...well done!

I'd make more vids but the weather is really bad this winter

I know what you mean. This winter, our temps have plummeted down into the 70's. Winter is always difficult.

[Brian the brain]

Imagine this:
Over here it has been minus 17!

Not a lie
!!
Although we Europeans use Celcius...



You Americans!

[POLAND_SPUD]

have you considered porting the barrel to help with accuracy

it has a silencer that should help with that... I wasn't using any sights in the first vid (80 metres) so I guess it is quite accurate..

right now I am limited to short range shots as everything is covered in knee deep snow and I've got some work to do

Where is the magazine ?

sorry I forgot to mention that it's not included in the pic. It's just a vertical aluminium tube. Its ammo capacity is about 20 rounds

Is the gun using an external air supply

yes, it uses external air supply (fridge compressor with a 10L tank). But I am considering using one of those 88g co2 cartridge to power it...

@BTB
it was even worse over here... -30 deg C

All you need to do now is swing the chamber around and elevate the sight.

A rod could press the trigger

yeah I was considering that. I think I'll just use a 1/8" QEV to move the trigger

@psycix
thx again for machining it.


But just to clarify this...
It's not that you need a machined block to build a gun like this. If you are lucky you might find these or you can just use standard fittings (though you'd have to sleeve the inside with a small tube)

[jackssmirkingrevenge]

Great stuff as always, 170 psi is fairly low though - are you planning on taking it any higher?

[POLAND_SPUD]

I've taken it higher but I didn't film that. I think that I might have some time tomorrow.. ....uhmm today

[POLAND_SPUD]

UPDATE

CLICKY

pressure - almost 400 psi and then it dropped... then I filled it up a bit again and at the end it was close to 250 psi
distance - 20 metres


sorry I didn't have time to zero the scope properly...
now I know it probably shots about 70 cm above the aiming point but there was no way I could see that while shooting because every time I got thrown off the target by the recoil

I guess that all the shots that landed more less where I intended were those I fired while not using the scope

BTW do you know of any editing programme that can use .mov files ?? the one included with the cam can only output in .mpg or .wmv formats with sh### quality but compact size or .avi with decent quality files but +1GB in size

aghhh!!

[Brian the brain]

Nice to see things are...ehm...looking up..


I love this thing..
Could you do a max ROF vid? It seems there is a long wait between shots...probably because you're aiming it..

But does it go bup-bup-bup if you want it to?

[POLAND_SPUD]

yeah that's because I was trying hard to prove it's accurate but that ended in an epic fail

but yeah it's not that I can fire 3 or 4 RPS... the airhose that I normally use is buried somewhere under the snow and I don't feel like looking for it now because rubber gets brittle in low temperatures

so right now I am using 1.5mm ID polyamid tubing to connect it to the tank. I guess that restriction lowers max ROF to ~1 RPS at full power
though on the other hand this tubing is quite cool as it's so light that it almost feels as if the gun was fully self contained

lol I've just noticed something... have a look at ~0:52 and that concrete columns there... I guess I've got to inspect those tomorrow