Combustion Sniper (UPDATE 1.2)

[freder]

It´s finished what do you think now?
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Hey there spudders,

I actually wanted to build a mini just for fun because I was bored

But it turned out a little bigger. So I gathered some stuff laying around and began to build this little spray & pray sniper. I have shot with it a few times already so it works

Specs:

Barrel - 15mm/ 42cm
Chamber - 250 ml
Stock - old woodn toy (modified a bit)

I think the pics will tell the rest!

I do have a question about the fueling. If I´m right with this:
The Chamber has ~250ml so I have to add gas of ~10ml = 4%?
Is this okay?

Tell me if you´d change anything

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Edit:
-I put some kind of guilly around it
-Added the piezo
-shortened the hose as much as possible!
+ I screwed it to the barrel

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Another Edit

-took off the hose thing
-replaced it with 2x 90° copper pipes
-Softair Reddot
-Laserpointer (just for looks) 8)

I´d like to thank starman. You were right the hose thing was a bad idea. It works much better now. Thx

[SpudsMcGee]

Cool, have you fired it yet...

[freder]

yes i have but its not that easy because the ignitor isn't built in
I´ll updated damage pics and that when its finished

[starman]

That rubber hose is rather dead spacey and long and soft and crooked so I believe it's going to eat up some of your performance. Also, I'm not sure I would want to shoot that thing with my eye and face so close to it....that hose only looks butt-spliced taped to the barrel....

Looks like you are using butane fuel so 4% should be about right. With propane you would want to push that up to 4.2-4.3%, with MAPP 4.8-5.0% or so.

[freder]

okay thanks about the fueling answer.

yeah its not fixed properly but i didn´t shoulder fire it yet,
just put it in the vise and fired it.

I´m going to try and see if I´d get more peformance with a brustdisk
between the chamber connection and the gardenhose.

[Radiation]

Man I gotta know, where do people get all these old gun stocks? It's just amazing to me that so many people just have busted up old guns lying around their houses.

[starman]

I´m going to try and see if I´d get more peformance with a brustdisk between the chamber connection and the gardenhose.

How about just completing a safe basic cannon before you start fooling around with a burst disk. There's a few fundamentals you need to attend to first.

[Ragnarok]

Looks like you are using butane fuel so 4% should be about right.

Butane should be at 3.2% with air, so 4% is too much and will hit performance slightly.

[starman]

Looks like you are using butane fuel so 4% should be about right.

Butane should be at 3.2% with air, so 4% is too much and will hit performance slightly.

It has been shown that a slightly rich mix from theoretically perfect actually provides a small bump in performance before falling off, thus all my numbers were bumped up a bit purposely. 4 is slightly higher than optimum but I would certainly be willing to guarantee the shot if everything else is in place.

[Ragnarok]

It has been shown that a slightly rich mix from theoretically perfect

Slightly rich - 4% is a full quarter over ideal. I'd be aiming for 3.5% perhaps, but not 4%.

[freder]

How about just completing a safe basic cannon before you start fooling around with a burst disk. There's a few fundamentals you need to attend to first.

well this isn´t my first gun and its just for a bit plinking.

[inonickname]

4%, the extra may be burnt in that hose. It will be hurting performance, try shorten it as much as possible. And dang at the chamber..I was worried about using DWV (non-pw) in a mini before... ( )

Pretty cool gun, the stock looks evil.

[starman]

4%, the extra may be burnt in that hose.

No doubt, the hose IS acting like part of chamber in this configuration.

[freder]

... And dang at the chamber..I was worried about using DWV (non-pw) in a mini before... ( )

I dont think its DWV. In Germany we have the orange tubes ( which I think these are the cheepe ones) and the grey tubes. These are "hard to enflame" and I also think they´ll take a bit of pressure

[POLAND_SPUD]

@freder
hi it's good to see that there are more people from EU here...

I dont have much to say about the gun itself as I am more into pneumatics but anyway - nice job

you should try to build a high pressure pneumatic as it's a kind of tradion that euopeans = high pressure guns...