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“Liquid” gas powered longrifle

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Unread postAuthor: THUNDERLORD » Tue Apr 22, 2008 9:25 pm

mobile chernobyl wrote:I'm not sure if paintballs have changed, but last time i checked they were round gel capsules with some sort of oil (fish oil sometimes) and die in the center. That presents a liquid filled capsul.

There have been endless discussions on rifling in paintball, and countless tests have proven it to be of no use, sometimes more often than not hampering accuracy, and it also has the added effect of degrading efficiency; if you don't believe me visit pbreview.com, or pbnation.com and search rifling, its kinda been beatin to death like the old plane on a conveyor belt argument. The problem with rifling a paintball barrel is that you induce a spin on said liquid filled capsule, well inertia's a [female doggy] in that sense, becuase of the short impulse placed on a paintball when accelerating during shooting. the liquid in the center presents inconsistent results and the accuracy of the paintball is jeopardized. This is a VERY SHORT explanation, and its not worth getting into on a SPUDGUN forum lol, if you disagree, go search on the aforementioned websites, and/or get learned in physics.

In general, if its round, smooth bore, if its oblong and doesnt have stabilizing assistance, rifled bore.

Also you will be able to use very low pressure compared to a paintball gun if your using even a 4ft barrel, since a spud gun operates in more of a HVLP manner, given the barrel is .68 ID, being biased towards .695 or .7 might actually help given the tolerances of pvc or whatever your going to buy in 4-6" is no where near that of a peice of machined aluminum hydraulic tubing, aka paintball barrel.


What he said and the other guys, but I wanted to add that propane smells like bottled fart gas, is illegal so will never have a commercial value and is dangerous to use inside.

BTW, I think with natural gas they put the smell into it by adding sulfur or something so if it leaks you'll know it. Not sure about propane though.
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Unread postAuthor: DYI » Tue Apr 22, 2008 9:43 pm

What he said and the other guys, but I wanted to add that propane smells like bottled fart gas, is illegal so will never have a commercial value and is dangerous to use inside


What the hell? Where do you live that propane is illegal? I've never heard of that anywhere. And you can't even smell propane, it's the odourant they add to it that makes it smell rather strong. Propane also doesn't smell like bottled fart gas, it's MAPP that smells like that.
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Unread postAuthor: judgment_arms » Tue Apr 22, 2008 9:48 pm

Have I ever mentioned I hate typing… :roll: :D

Ragnarok, I thought porting worked best when it went entirely around the barrel’s circumference?

Bluerussetbouy, sorry, I meant Pennsylvania Rifle, my parent were rushing me to get off of here so we could go eat; didn’t help that I had the song“Hunter’s of Kentucky” stuck in my head…

Mobile Chernobyl, I’ve read those reviews and found one thing in common: they were all based off paintball gun platforms, as such they had short barrels (12-14 inches) and accelerated the paintball far to fast, never mined the fact that the naked paintball couldn’t have engaged the rifling to well, other wise it would have burst.

I have already made a prototype paintball rifle that had a bore rifled to 1-in-102 and about 18.5 inches long, according to the GGDT it ws shooting at 302fps and I saw a slight long range improvement in accuracy over my stock Tippann 98c.
Ragnarok brought it to my attention that 1-in-102 was far to slow if a twist rate to stabilize the paintball properly so my new barrel will have the much more appropriate ROT of 1-in-14.

Joannaardway (if I spelled that wrong, sorry) and a few others, I believe Ragnarok was one of them, and myself discussed rifled paintballs and came to the conclusion that if you got it up to speed slowly it would give it time to properly distribute the weight, and that the longer it remained in the barrel the better distributed the weight would be.
I have full faith that my barrel will work, provided I can accelerate a paintball to 300fps slowly enough.

My original plan was HPLV with a slow opening, small bore, valve that essentially allowed the compressed gas to “push” the paintball up to 300fps, rather than hammer it out the bore like a faster valve would. Also, need I remind you of Rifled Musket?

In general, if its round, smooth bore, if its oblong and doesnt have stabilizing assistance, rifled bore.

No offence sir, but that line is a load of manure, unless of course the round ball used in Hawken, Kentucky, Pennsylvania, and plains rifles were not round… nope, just reached into my hunting pouch, they’re round.

I’m using spiral rifling, I have heard of linear rifling, personally I don’t think it’s worth it.

Also, another reason for the long barrel, I shoot Creedmoor style and I’m nearly 6 foot tall.
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Unread postAuthor: THUNDERLORD » Tue Apr 22, 2008 10:03 pm

DYI wrote:
What he said and the other guys, but I wanted to add that propane smells like bottled fart gas, is illegal so will never have a commercial value and is dangerous to use inside


What the hell? Where do you live that propane is illegal? I've never heard of that anywhere. And you can't even smell propane, it's the odourant they add to it that makes it smell rather strong. Propane also doesn't smell like bottled fart gas, it's MAPP that smells like that.


I meant, It's illegal to use it like that. I don't want to go into details but for example just read the label on the can about refilling it (similar).
And if you put it into pipe also that would also probably be an "unapproved container".

The propane I have Does smell like bottled farts and IS dangerous to use inside.
I already stated that it may be the "odourant" added to it and that I don't know if that's the case in propane(either way it stinks).

But yes, if you design something that uses propane to propel stuff more than likely you could get in big trouble if you sold it commercially. Sorry to be a buzz kill.

If you want to keep taking risks it's ok. There's also a do not remove tag on furniture. But if you remove it and your selling it you could get in big trouble also if it's commercial.

So go ahead and design something that uses pressurized propane as a propellant and try to sell it if you don't believe me.
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Unread postAuthor: judgment_arms » Tue Apr 22, 2008 10:08 pm

Who said anything about selling it? and I thought I done said I wasn’t going to use propane, I changed my mind on that.
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Unread postAuthor: THUNDERLORD » Tue Apr 22, 2008 10:51 pm

judgment_arms wrote:Who said anything about selling it? and I thought I done said I wasn’t going to use propane, I changed my mind on that.


Hello Judge, I was really just stating one disadvantage. Even if you don't plan to sell it when you are building it what if you stumble onto something new that would have a huge commercial value but the way you designed it makes that impossible?

Myself I try to have general rules of thumb in designing, such as:

----Being legal as possible.(This may save you a ton of grief)

----Using standard and readily available components.: so others can build something similar or your idea could be mass produced commercially to make you $$$Rich one day possibly!!!

-----Using parts with specified ratings wherever possible. You might find some useful junk but it can never be replaced or you won't know if it's safe.

-----Other safety considerations:
A lot of stuff I want to design I plan to give to relatives or best friends as gifts.
That would be a nightmare if they got injured/ burned their house down.

or what about public displays, if someone even got a scratch and it was your fault you could have a major problem.
Actually I worry about myself the least.

I was just giving you advantage or dissadvantages, I was hoping you'd find helpful 8)
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Unread postAuthor: judgment_arms » Tue Apr 22, 2008 10:58 pm

Yeah, I know all about safety, part of the reason I started this thread in the first place.
As for propane, Tippmann makes a propane powered paintball gun, and all green gas airsoft guns run off the stuff.

I don’t know were you live, but ‘round here there ain’t no laws against using propane, the warning on the bottle is basically a legal disclaimer.
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Unread postAuthor: Ragnarok » Wed Apr 23, 2008 10:02 am

judgment_arms wrote:Ragnarok, I thought porting worked best when it went entirely around the barrel’s circumference?

Yes, for two reasons.
In theory porting just the base could result in an unbalanced force that would create a slight muzzle rise, but at low pressures, that wouldn't be too big a problem. Of course, it wouldn't be vaguely suitable for a high power spudgun - there you'd need porting on all sides to create a net force of zero.

Also, if you had more porting holes, you could vent the gas faster... which would bleed off more gas, and thus lessen muzzle blast further.

However, it comes down to what you think would be best.
Ragnarok brought it to my attention that 1-in-102 was far to slow if a twist rate to stabilize the paintball properly so my new barrel will have the much more appropriate ROT of 1-in-14.

Joannaardway, a few others, and myself discussed rifled paintballs and came to the conclusion that if you got it up to speed slowly it would give it time to properly distribute the weight, and that the longer it remained in the barrel the better distributed the weight would be.
I have full faith that my barrel will work, provided I can accelerate a paintball to 300fps slowly enough.

Paintballs are far from ballistically perfect. They've got low density, and are spheres, which gives them a disappointing ballistic co-efficent, equivalent to about 0.02 G<sub>1</sub>. However, low ballistic coefficient doesn't make something intrinsically inaccurate, it just limits effective range.
Wind and air density changes will affect range, but with a little application of common sense, that's not hard to compensate for.

Now, their liquid core does also create some inertia problems - if they're accelerated too fast.

Now, I'm sure you all know the old trick to tell the difference between a boiled egg and a raw one - spin them both, then touch them with your finger just long enough to stop them spinning, then let go again.
The raw one will start spinning again after your finger has been removed, as it's core has inertia and keeps spinning.

Now, there are important differences between an egg and a paintball. Where as egg white is fairly runny, (although much more viscous than water), paintballs are filled with a deliberately thick and sticky fluid (Polyethylene glycol), so it sticks to people better.

Also, when made, the process causes the paint inside to be under slight pressure from the skin which contracts on cooling - which is what makes paintballs firm, and helps to maintain their round shape.

Last, but not least, a paintball is smaller than an egg, which means that the spinning torque is effected on the core more effectively.

This means that when a paintball is spun, the core is much more wont to follow the skin than with an egg. That's why if you try the same egg trick as I talk about above but with a paintball, it won't start spinning again.

Especially if spun up over several feet, and thus over more time than a short barrelled paintball gun, there shouldn't be any concern about it.

Of course, you don't need my complex explanation to reach this conclusion. Just ask yourself, if you couldn't successfully spin a paintball, why would paintball guns deliberately try to achieve back spin?
If it had no effect, then the companies wouldn't waste resources on it.

Now, having thought that idea through, it does create another interesting thought... could a projectile filled with a low viscosity liquid, be used accurately?
If the core itself was next to immune to spinning effects (a major cause of inaccuracy), then the minimal mass of the projectile's surface wouldn't be able to generate significant Magnus forces to affect trajectory, and would quite quickly be slowed down by friction with the air.

I suspect it might not be completely effective, and producing a projectile that would properly benefit from it would be a little difficult. Still, unless it's tried...

Also, another reason for the long barrel, I shoot Creedmoor style and I’m nearly 6 foot tall.

Hmm. I'm 6' 2", and although I have used spudguns with barrels that long, my current preference is for barrels a little under 4' (120 cm to be precise) in length.

Longer than that, and it doesn't feel quite as "real", because it's too cumbersome and large. (HEAL's current overall length is 144 cm, a hair less than the full length Barrett M82, at 144.8cm)
With the scope and bipod, it does look like a quite convincing AMR (although my original plan was to look more like a shotgun, but hey, who cares) - which is part of the cool really.

Although I know it's not really one, there is that real sense of: "Hey, I'm firing a high power rifle" when I'm using it, with looks, firm recoil and all that building into a neat effect.
I just can't get that from a launcher that doesn't have some kind of "authenticity" to it.

So I can understand why you're looking to build a replica long rifle. It's not going to be fully practical, but heck, if it gives that feeling of cool, who gives a damn?
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Unread postAuthor: judgment_arms » Wed Apr 23, 2008 12:46 pm

Ragnarok, I think I’m going to leave off the porting, if I make a more modern one I might port it, but for the longrifle I’m going to leave it un-ported.

You know what; I need to go around a save all your ballistics related posts in a Word document for future reference… :)

You do know what Creedmoor style is, well for those who don’t it’s were you lay on your back and rest the muzzle of the gun on the tips of your boots to shoot; that’s why I need the long barrel.
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Unread postAuthor: Ragnarok » Wed Apr 23, 2008 2:15 pm

judgment_arms wrote:Ragnarok, I think I’m going to leave off the porting, if I make a more modern one I might port it, but for the longrifle I’m going to leave it un-ported.

Sounds fair enough, I can see it wouldn't look quite right.

I'm never too fussed about exact looks - just pick and mix things I want. I mean, just look at HEAL... Bit like a shotgun, but with a FAMAS grip, basic breech loader, target rifle bipod, and an airgun scope (no, seriously - what else was I meant to get in the UK nanny state?)

You know what; I need to go around a save all your ballistics related posts in a Word document for future reference…

Actually, I do something a little like that myself. Most times I have a new idea, I'll note it down in a Word document to come back to later.

There's even something that would pass as a short thesis on how to get a spudgun (although mostly pertaining to smooth-bore ones) to shoot accurately - given I want to try hitting at hundreds of metres, I've had to think about it in some depth.
I've been planning on finishing it up and posting it in the Theory section some time, although it's taking some time.
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Unread postAuthor: judgment_arms » Wed Apr 23, 2008 5:31 pm

Ragnarok wrote:
You know what; I need to go around a save all your ballistics related posts in a Word document for future reference…

Actually, I do something a little like that myself. Most times I have a new idea, I'll note it down in a Word document to come back to later.

Great minds think alike; or is it stupid is as stupid does? :D

There's even something that would pass as a short thesis on how to get a spudgun (although mostly pertaining to smooth-bore ones) to shoot accurately - given I want to try hitting at hundreds of metres, I've had to think about it in some depth.
I've been planning on finishing it up and posting it in the Theory section some time, although it's taking some time

So, do you want me to badger you about that too? :D
While we’re on the subject; is the LRC done yet, you bean workin’ on it even?:lol:
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Unread postAuthor: Ragnarok » Wed Apr 23, 2008 7:32 pm

judgment_arms wrote:Great minds think alike; or is it stupid is as stupid does?

The first... I hope.

Truth is, I learnt the hard way about not writing ideas down somewhere - I spent some considerable time trying to recall a particular design I'd not recorded, and although I did eventually remember it all, it was a little tedious.

So, do you want me to badger you about that too?

Oh dear... I knew I shoulda kept me trap shut. :P

I do actually have a ridiculous number of articles about different spudgun subjects, perhaps even enough to write a short book on the subject.

The reason is, I tend to come up with some of my best ideas when writing articles or longish explanations, and so, I sometimes deliberately start writing something to try and spark ideas. It works quite well.

None of these articles are quite up for "release" yet, but I'll see what can be done.

While we’re on the subject; is the LRC done yet, you bean workin’ on it even?:lol:

I have been working on it, as and when I find the time.
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Unread postAuthor: DYI » Wed Apr 23, 2008 7:46 pm

So go ahead and design something that uses pressurized propane as a propellant and try to sell it if you don't believe me.


I don't need to, all of the "Green Gas" propelled airsoft guns have proven my point for me.

You may also realise that the label on the bottle says that a non-refillable propane cannister which has been refilled is illegal to transport on aircraft (and possible commercial trains and boats, I can't remember), not illegal to posess.
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Unread postAuthor: judgment_arms » Wed Apr 23, 2008 7:54 pm

Ragnarok wrote:Truth is, I learnt the hard way about not writing ideas down somewhere - I spent some considerable time trying to recall a particular design I'd not recorded, and although I did eventually remember it all, it was a little tedious.

Been there, done that… you’ll be surprised how much time I’ve wasted because I didn’t want to waste any time writing stuff down. :roll:




I do actually have a ridiculous number of articles about different spudgun subjects, perhaps even enough to write a short book on the subject.

If you do write a book, I’ll gladly buy a copy; provided it’s not over $20.00us, unless it’s as thick as an unabridged dictionary.

The reason is, I tend to come up with some of my best ideas when writing articles or longish explanations, and so, I sometimes deliberately start writing something to try and spark ideas. It works quite well.


Funny, I come up with my best ideas late at night when I’m dog tired… come to think of it, when I’m trying to explain something to somebody I usually come up with a better way of doing it…


You know, we got a little off topic… oh well, it’s my thread and if I take it off topic so be it.

What do you think about my idea of using a small spring-loaded ball-valve in my rifle, or… what about having a chamber were you put a Co2 powerlet with a hammer that runs the powerlet into a nail to allow the Co2 to run out and push the paintball down the barrel.
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Unread postAuthor: Ragnarok » Wed Apr 23, 2008 8:17 pm

judgment_arms wrote:If you do write a book, I’ll gladly buy a copy.

I hadn't really thought about it that way... but as an idea, I like it. (EDIT: On second thoughts, it would probably be better as a freely distributed e-book/Word doc/pdf or something. I wouldn't fancy the attention that could arise if I try to get it through a publishers.)

Come to think of it, when I’m trying to explain something to somebody I usually come up with a better way of doing it…

I get that sometimes. I'm torn between considering it annoying or useful.

For now, I think I'll have to settle for annoyingly useful.

what about having a chamber were you put a Co2 powerlet with a hammer that runs the powerlet into a nail to allow the Co2 to run out and push the paintball down the barrel.

Although an interesting idea, it is wasteful.

A 12g sparklet bulb contains something like 600-700 Joules of energy. A single paintball at 300 fps is around 13 joules - which would yield a rather low ~2% efficiency, assuming one bulb per shot (I can't see that the hammer idea could achieve more than one shot).

It would also be hard to contain with a barrel that long. Most likely, the paintball would attain over twice the intended velocity, if not more.

As for sprung loaded ball valves... they're a forgiveable offence :D, depending on what exactly they're used for.
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