Plans for new rifle - NEW QUESTION

Thursto · Sun Oct 19, 2008 4:38 am

Hey guys,

i'm starting to get back into the spud gunning

My plans are to build a Pneumatic inside of a Sterling rifle stock.

I want it to be all metal, now here comes the questions:

Does the paint design show any flaws? I've never made a piston, but theres always a first time for everything, not sure what size galvanised T it will go in, but any recomendations for material for the piston + face?

The chamber will be about 10-15cm long, about 1 1/2" wide galvanised steel.

Ill be running it of those C02 tire inflators, and ill have a shock pump mounted onto the bottem for the extra high power shots.

The barrel will be 10mm Aluminum and not sure how long.

***EDIT***:

do these canisters work in those c02 tire inflators? they are like cream chargers or something i think they are n2o

Here's the design:

POLAND_SPUD · Sun Oct 19, 2008 5:39 am

if you want to use 10mm barrel then a 3/4" qev would be an overkill... a 1/2" wil be just fine... however you might consier getting a 15mm barrel becasue it will be easier to find ammo for it... if you do so then it would be good to have a 3/4" QEV...

generally I advise you to buy the larger one.. the difference in price is not that big and you can use it latter for your next gun or use larger barrels for this one etc.

Thursto · Sun Oct 19, 2008 5:42 am

Hey!

Ok, any ideas where i can get one?

Im in Australia does BC Arms have them and ship to AUS?

Or does anyone know somewhere better?

I think i'd for the 1/2", Whats the pressure rating like on them?

POLAND_SPUD · Sun Oct 19, 2008 5:59 am

mcmaster has them and I think they ship them abroad... but I think that it will be cheaper for you to buy them locally... either use google or ask MrCrowley and some other members from aus - I am sure they will help you

al-xg has used his QEV at ~800 psi... I use mine at 400 - 450 psi without any problems.... (NOTE I am talking about 'european' QEVs - I'll post a pic of it later I got to go)

seriously consider switching to larger barrel and a 3/4" QEV - you'll get more power for a few $ more.. plus it will be much easier to find ammo for it... (I am sure that other members will tell you exactly the same)

Thursto · Sun Oct 19, 2008 6:05 am

Oh alright ill PM some Aussies about them.

Serious? I thought they were rated to like 200PSI MAX
Learn something new everyday !

Ammo is not a problem, i fire 9mm Lead sinkers (I get them hell cheap)

My plans are changing tho...

Im thinking keeping the same setup, with the barrel and QEV but smaller chamber, and use a c02 tire inflator.

Anyone know how much pressure you'd get out of one of those bulbs? and say i wanted each shot at 100PSI how many shots will i get out of one bulb.?

In the procces of better paint drawins!

Demon · Sun Oct 19, 2008 6:26 am

Anyone know how much pressure you'd get out of one of those bulbs? and say i wanted each shot at 100PSI how many shots will i get out of one bulb.?

Of what i know about co2 tire infaltor, you will get approx. 3-4 shots

Thursto · Sun Oct 19, 2008 6:30 am

Ok cool thanks, i just need to get my hands on a QEV and the stock, if i dont get the stock, ill jst make one.

Anyone able to run some data through that program ddgt of w/e? I havent used spudfiles in so long i'm loosing my knowledge.

Just want to know how performence would be with the following:

1/2" QEV
1 1/2" x 10cm Galvanised Steel chamber
10mm x 50cm Barrel

C02 at 100 PSI

Demon · Sun Oct 19, 2008 6:36 am

MMMM(brainstormingMMMMM

i will say approx 400-600fps...

Be sure then your barrel is perfectly circle if you want max power and accuracy.

Thursto · Sun Oct 19, 2008 6:41 am

Is that sarcastic?

But none the less the barrel is circulat enough and is fairly accurate
(ive used it on a 1" Sprinkler valve with a 2" x 30cm PVC CHamber)

Thanks,

Demon · Sun Oct 19, 2008 6:47 am

Is that sarcastic?

Nope, it is called an estimation...

Thursto · Sun Oct 19, 2008 4:26 pm

Fair enough, 400FPS is good enough for me.

Just need to get a QEV, they have them on ebay by anychance?

daberno123 · Sun Oct 19, 2008 4:55 pm

There are usually a few QEVs up on eBay, some are ridiculously priced though. To get a closer approximation on velocity try running your gun through GGDT.

Pyro Ninja · Mon Oct 20, 2008 3:13 am

Hey, I hope experament_u2 doesn't mine me using this.

Id say that you wont need a chamber as big as you specified, and a 20mm brass Tee should suffice, use brass instead of galvanized steel as brass fittings have much nicer threads then gal (but are more expensive)

As a piston, use a rubber cork as they create a 'perfect' seal and don't break, (well not for me)

Thursto · Mon Oct 20, 2008 5:15 am

Hey pyro ninja

Yeh money is not that big of a problem.

So ill go for brass, and that picture is almost exact to what i want, except ill have a small chamber going under like in my paint drawing.

I Wont this to be VERY powerful.

What type of trigger did experament_u2 use in that cannon?

And a rubber cork? do you mean like the wood kinda ones?

Like these:
http://www.planet-science.com/about_sy/ ... /corks.jpg

Mitchza89 · Mon Oct 20, 2008 5:45 am

I'd stick away from the rubber corks mate. I got right into em' for a while but realised they aren't at all practical. They need constant lubing otherwise they stick like a bitch, plus they're heavy, and hard to get perfect fitting in your pistin housing.

They sell em' at Clark Rubber. They are used as a "plug" in bottles and what not. You need to sand them down into a cylinder because they come in like a..."pyramid" style shape but with a flat top. It's rather hard to get it into a cylinder good enough to make a good seal in ya piston housing.

Best to stick to cast epoxy or hot glue mate. I'm using machined aircraft aluminium 'o' ringed pistons at the moment... they work well

.