Deathray Marble Machine Gun

[Hotwired]

Ah yes, nothing beats the vertical piston QEV for making a bullpup

That bolt really does look qute nifty from the diagrams.

Still no word of any test fires?

[POLAND_SPUD]

BtB does your QEV works fine at 20 bar ?

LOL post some vids or dammage pics... I can't wait to see it in action

[Hotwired]

It should do, it's the same model that gets used at 300psi (~20bar) over here.

[Brian the brain]

I still need to get the bottle refilled.
pumping the CO2 bottle up to 20-ish bar gets me tired real quick...

All I've done so far ( between these latest improvements) is 5 round bursts at 13 bar.One time the bolt got stuck after 4 shots.I need to find whatever it's snagging on if this occurs more often.
I need the CO2 refill to test it further.
I have to tinker with the adjustable pop-off to make sure it works at the highest possible pressure and still "pops". a pssshhtt won't do

With this larger chamber it will most likely be a little louder and will waste a little more air.Well...waste might not be the right word.It might just up the power.Put a little umph behind those marbles.

Because the pilot volume is so small it will be refilled in a split second after the pop-off has closed so there is a limit to how long the valve stays open.( also the bottle valve can be used to regulate flow)
This will ensure it won't be wasting gas like the old MMG did.

I'm counting on the results Ragnarok ( among others) have had with this kind of QEV.Rag uses 23 bar so... I should be fine

[Acdcmonkey1991]

This thing is so awesome I can't wait for the videos. Btb, you have come up up with some powerful kickass guns (my favorite is still the riot gun)

[POLAND_SPUD]

for me even semiauto would be great
you know u could build a compressor like the one I've built. It would take 4 - 5 minutes to fill that co2 bottle to 300 psi - but it's still better than having to pump it yourself...

BTW u would probably waste less air/co2 if you could find some way to close the air inlet while the pop-off valve vents the pilot side (you know so that the pressure hose won't increase your pilot volume and the valve wont have to vent the air that is there).
I think that it could be done using a kind of 3 way valve that would vent itself (and pilot the QEV) when the pressure reaches set level and close the air inlet at the same time.

[Brian the brain]

Deleted double post.
Just read the sawed of remark.It still holds a special place in my heart.
Although I can no longer choose between the sawed off and this one.
Overkill is cool in a different way...it just has raw power

The sawed-off has become a classic.It' s hard to top that

[SpudFarm]

WOW that`s a pure dream! ohh i cant look at it just get sick of "want it sickness"

[Brian the brain]

I have made some minor adjustments wich make a huge difference.
I tried out the gun to see what the damage was ( still with the aid of the track-pump) and it was VERY disapointing!!

Although it was capable of full auto( jamming bolt is fixed) it was lacking power.I could not even shoot through an acoustic guitar.
THe QEV opened to shortly for the gun to have any real power.THe pop-off closed off the pilot too soon.

I decided to build my own pop-off.One that would ALWAYS pop open and never hissssss open, and would dump the entire pilot very quickly.
I had a theory on it for some time now.

I gave the outlet on the pop-off a relatively small diameter( a male quick disconnect fitting), and the piston that closes it a large diameter( 1") and a longer travel to the vent hole.

A heavy spring keeps the piston on the outlet.Once the small hole starts to leak, the pressure hits the larger surface of the piston ( almost airtight)and because of the much greater force this provides the piston snaps back.
Every time, even when pressure rises very slowly...just..BANG!!! the valve goes off..I could not be happier ( not with my pants on anyway ).
The plume of vapor that blasts out of the venthole is over a foot long!
Offcourse the 20 bar helps too ( 300-ish psi)
Needles to say it actuates the QEV like a MUTHER!
Pressure is adjustable.The valve pops violently from 3 bar up to the 20 bar maximum.( I need a stronger spring!!)

FINALLY SOME REAL POWER!!!

I also used a small pop-bottle for a hopper.I like the way that looks
I still need to paint.

Time for some pics..

(Oh and please leave some comments..I've put a lot of work into this, I would like to know what you guys think..)

[Novacastrian]

Wow that is a very cool looking gun indeed Brian, what rate of fire do you expect? I would so love to empty a hopper from this gun!
Great work mate

[ALIHISGREAT]

damn you just made me one jealous little f*ucker i would love to see a full hopper put throuh that beast and i am fascinated by the home made pop-off could you post some more details? damm i'm soo jealous

[Brian the brain]

I'll try as soon as I have the money to refill the bottle.( got a baby coming, so..)

I am actually a bit scared to try too you know...
if I were to be hit be a recochet, I would be having a rather hard time smiling for a while, you know what I mean..
ROF fire will be quite impressive, although not like a bbmg, ofcourse..The bolt now feeds faster than the eye can see.Very smooth, no more snagging or whatnot.

I will also need to buy a LOT of marbles ( not all of em fit)
And I need some place with only deaf people nearby. It will most likely surpass all my previous guns in loudness due to the rapid succession of already loud shots.
Think 1/2"QEV at 20 bar...times the number of marbles this hopper can hold ( 30-40??)

Nice to see you like it.
Damn. I need video with sound..BAD!!

details will come later..it's 12 in the evening over here
I'll try a parts list and a how to...It's quite simple now I know what works.
The process to get to that point however was a bit more difficult

[ALIHISGREAT]

hmm if you don't want ricochet then you should shoot at some thing really hard so the marbles just turn to dust, or to save money you could just shoot a target rigged up to stop and catch the ammo and put a sheet of cardboard over the front as a target?

[Brian the brain]

If I wanted to shoot cardboard I'd build another rubber band gun hahaha

Something really hard is what causes the ricochets in the first place.I need to set the target at an angle and make sure there's nothing behind it
with a surface facing me.

Shall I name the valve I created?? A Snapvalve perhaps??

Or an Adjustable Quick Exhausting Pop-off??

[ALIHISGREAT]

from the way you described it the snap valve seems an appropriate name and card board was just the first thing that came to mind, it would allow you to demonstrate the rate of fire and accuracy without damaging the ammo... maybe you could use some thin wood instead or thin sheet metal?