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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: mobile chernobyl » Sun Apr 27, 2008 9:31 pm

judgment_arms being educated by Mobile Chernobyl wrote: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.

14" or 48" there both leaving the barrel at 300 fps. Yes the impulse time is different, but considering the inertia of the fluid inside, your going to need a little bit longer impulse than even your talking about to achieve a spinning effect similar to that of a bullet.

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.

I hope your not comparing accuracy to that of a stock tippman barrel? For your sake, I will assume you were conducting your rifled barrel accuracy test compared to that of a proper multi bore paintball barrel kit, properly matched to the size of your paintball, with humidity being a concern and NOT your stock tippman barrel. If this is not the case, lol.

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?

Need i remind you that "rifled musket" technology is prevalent to the early 1800's and the current year is 2008?

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.

One thing you seem to keep neglecting is the fact that the amunition used in these super high tech 1800's "rifles" were patched SOLID balls. Paintballs are not SOLID and therefore there WILL be a difference in their ballistics, and even if you do patch them, it still doesnt change the fact they're filled with a liquid and since it is liquid in a sphere, the fluid will have different angular velocitys relative to the center, and you may get a slinky effect where the speed of the outermost fluid accelerates first because of the friction with the casing, then transferring the rotation to the inner fluid mid flight. This is the least of your worrys tho, and what will most likely happen as you increase rifling per given length is you will cause the paintball to expand radially along the z-axis (axis from barrel to target) This effect is used purposely on solid bullets, causing them to expand and grab into the rifling of the inner barrel walls. Unfortunatly for your soft, gelatin walled paintball, this fluid pushing out radialling from the z-axis on the gelatin walls will cause it to expand and further more increase it's drag coefficient. This is of course IF you can even cause the fluid to spin, with the short impulse it will see vs the intertia of its inner fluid. If you really wanna "snipe" with paintballs go put an 18" Snyper barrel on your tippy and call it a day.

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

When talking about paintballs aka liquid filled spheres I agree, rifling is not worth it no matter what kind. With paintballs you are dealing with both aerodynamics AND fluid dynamics - this is not so with solid lead ballzz. Your best bet is the best quality paintball, with the smoothest exterior, so IF it does spin, it does not have anything to "grab" the air (think slicing in golf and high/low pressures created with a dimpled golfball to create spin), fit into a barrel that it fits precisely within .001" for appx 1/3-1/2 of the overall initial length. Hmm this all sounds very familiar, oh yea thats right, its ALREADY been researched and developed thoroughly in the paintball industry. You can e-argue about paintball ballistics all you want, but unless you conduct some seriously thorough tests with ALL variables taken into respect and regulated, your arguement holds no ground to what is currently held as "true".


However this is your gun, and I'm assuming you'd rather not use the latest technology to make it accurate, so it is perfectly understandable if you want to base it off of 1800's technology.

If your actually going to play scenario games or w/e with this, i would just work on creating a 1in14 barrel that threads to a quality cheap gun like a used SP Ion. It will work more reliably, consistantly and give you a higher ROF than anything based on "spudgun" tech.

Ragnarok - "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."

You're referring to two different ballistic properties here.

"Backspin" is an aerodynamical effect where the backspin causes lift to alter the trajectory of the ball. And the "companies" do this far differently than rifling. they use a curved barrel, which works far differently than a rifled barrel to achieve spin.

"Rifling" is a gyroscopical effect used on cylindrical objects to create spin along the z-axis for ballance in flight. This is not required for a round object as there is even distribution of density radially from the Cog, not so with a normal cylindrical bullet.

This argument is stupid and if you believe round objects require rifling to produce spin and therefore become more accurate, then news for u the world is not flat. A little research tells me that rifling was created for a different reason with round balls. originally rifling was created, and called soot grooves, it would allow the soot to be pushed out of the barrel after every shot, minimizing the build up of soot (since BP quality back then was not always consistant and/or the best, and caused higher amounts of soot and residue to be left after each shot that would normally have to be removed by means of a cleaning rod), and consequently, improving accuracy with this "round balls", and not PRB. the problem then later arose with more aggressive rifling on round lead balls leading to deformation of the shape, not in a good way. This effect was later taken advatage with and used in the minie ball design, one of the first non spherical designs that was designed to purposely expand from the shooting pressures and expand radially to catch the rifling grooves and cause the gyroscopical miracle of rifling. rifling allowed the slightly cylindrical/not spherical object to true itself in flight, and not tumble in the x or y axis, sort of like an arrow. I'm sure you know the rest, but basically, the paintball is not ment to be an accurate ballistic body. The airgun version of this does not need "Soot grooves" because, hopefully your gun is not creating any soot! The paintball is ment to be fired in quantity rather than quality around 100 yards or less and to spread a paint like substance upon impact. originally it was used to mark trees for cutting. I'm done :)
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Unread postAuthor: Lentamentalisk » Sun Apr 27, 2008 10:11 pm

to summarize what that guy just said for those of you who don't have 3 hours on their hands:
It cant be done because rifling doesn't stabilize spherical ammo.
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Unread postAuthor: judgment_arms » Sun Apr 27, 2008 10:11 pm

Friend, your pushing your luck calling me stupid.

I’m going to reveres order:

In all my years of researching I’ve never heard of “soot grooves”, the powder residue was called “fowling” not “soot”; that alone shows me you know not what you’re talking about.
Rifling was invented for the sole propose of improving accuracy.

I don’t care what you say, by saying that rifling has no affect on roundball your calling thousands of longrifle manufactures idiots, explain to me why the St. Louis Hawken, which was made for roundball, has a rifled barrel and is far more accurate than a smoothbore musket.

Backspin and rifling both put a spin on a roundball to improve its ballistic performance.
The Apex barrel is not curved; rather it has a piece of rubber at the muzzle to induce backspin.

Need I remind you that 1800’s technology is just as deadly as 2000’s technology, actually more so considering the increasing use of “less-lethal” weapons.
And a good longrifle is just as accurate as a modern target rifle within it’s range.
Oh and, I LIKE THE STYLE!!! There is infinitely less to go wrong with a longrifle than with a modern assault rifle.

If I had the 300 dollars for the top-o-da’-line barrel… I’d probably by a firearm… yes I’m using the stock Tippmann barrel, the one that I can put cheapo china-mart paint on a 2litter bottle at 30 yards with.

What the heck are you talking about?


Your obvious ignorance to other matters you argue in your post, the ones on 1800’s technology, make me wonder whether you know what your talking about when it comes to paintball ballistics.


If your actually going to play scenario games or w/e with this, i would just work on creating a 1in14 barrel that threads to a quality cheap gun like a used SP Ion. It will work more reliably, consistantly and give you a higher ROF than anything based on "spudgun" tech.


1, paintball has to be wadded to allow it to bite the rifling with out breaking
2, ROF means squat if you can’t hit anything
3, by saying that a Co2 paintball gun would be more consistent than a HPA pneumatic rifle your showing your stupid side again.
4, I done explained all this once!

Edit: to your last line:
At 300fps a paintball has a maximum range of ~80 yards, and your average marker has an accurate range of 30 yards.
Also, the original markers were made for marking cattle at 5 yards, then came the idea for marking trees.
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Unread postAuthor: Lentamentalisk » Sun Apr 27, 2008 10:36 pm

Go Judge! Go! Fight! Fight! Fight!
Mobile, I would like to see you hit him with you paintball gun before he snipes you down from 1000 feet away...
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Unread postAuthor: judgment_arms » Sun Apr 27, 2008 10:50 pm

Lentamentalisk wrote:Go Judge! Go! Fight! Fight! Fight!
Mobile, I would like to see you hit him with you paintball gun before he snipes you down from 1000 feet away...


As funny as that is, sniping’s not my cup-o’-tea, I prefer shoulder cannons (usally 2 inchers), the paintball rifle is just an experiment to see if it works as nobody has yet tried the same method I’m using.

Although, if Mobile Chernobyl’s got enough grit, an honor duel would be fitting; swords, pistols, or shall we just chose are melee weapon of choice? :D
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Unread postAuthor: jimmy101 » Mon Apr 28, 2008 12:46 pm

"Rifling" is a gyroscopical effect used on cylindrical objects to create spin along the z-axis for ballance in flight. This is not required for a round object as there is even distribution of density radially from the Cog, not so with a normal cylindrical bullet.

Sorry, but that simply isn't true. Only in a high school physics course would that be considered correct.

The density from the COG may well be evenly distributed but that is only relevant if the projectile has zero spin. Since all real projectiles will have some spin the drag is not evenly distributed. Since it is drag that controls the flight path and not density/COG, it is the drag you need to consider.

Baseballs can be made to sink, rise or hook left of right depending on how they are spun. The same with golf balls, and every other kind of spherical object you can imagine.

The most important reason for putting spin on a round shell is not to give it lift, or drop or curvature, it is too make it do the same thing every time. Before you can get accuracy with a projectile you must first get consistence. You can greatly improve the consistence of your shots by spinning the round. Doesn't matter how you spin it (radially, back, top, side…) as long as you give it the same spin every time.

Paintball markers use backspin since it increases range a small amount (which probably really isn't very significant), and significantly increases shot-to-shot consistence. A curved barrel is used because it is a heck of a lot easier and cheaper to manufacture than a rifled barrel. Plus, the curved barrel gives you a small ability to hook shots around obstacles by rotating the gun.
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Unread postAuthor: Ragnarok » Mon Apr 28, 2008 4:23 pm

mobile chernobyl wrote:Ragnarok - You're referring to two different ballistic properties here.

Paintballs are not SOLID and therefore there WILL be a difference in their ballistics, and even if you do patch them, it still doesnt change the fact they're filled with a liquid and since it is liquid in a sphere, the fluid will have different angular velocitys relative to the center, and you may get a slinky effect where the speed of the outermost fluid accelerates first because of the friction with the casing, then transferring the rotation to the inner fluid mid flight.

Then answer me this: If a paintball could not be successfully spun up in rifling due to it's liquid core, why should the induction of backspin work?
As you yourself put it, paintballs are the same in all directions - if back spin works for them, rifling can be implemented.

I know rifling and backspin are different - but they are both spin, if in different directions. If backspin can be induced, it is illogical to say that rifling cannot be used.
As I said before, the paintball's core is so thick that unless you are spinning it up at completely insane rates, it's liquid core is fairly insignificant.

And the "companies" do this far differently than rifling.

Well... tell me something I don't know. It's obviously a different method.
However, it's not about the method, but the possibility. It can be spun on either axis with equal success.

"Rifling" <snip> is not required for a round object...
This argument is stupid and if you believe round objects require rifling to produce spin and therefore become more accurate, then news for u the world is not flat.

Can we not keep this discussion civil? There is no need to imply that any "argument", person or whatever is stupid.

Rifling does apply to spheres, for two reasons:
- It prevents them from taking another, undesired spin that would affect trajectory.
- No sphere is perfect, so will act in the same way as any other rifling, cancelling out any trajectory curve from unequal drag on each side.

A little research tells me that rifling was created for a different reason with round balls.
Originally rifling was created, and called soot grooves, it would allow the soot to be pushed out of the barrel after every shot, minimizing the build up of soot

This is a commonly quoted fallacy.
Rifling actually worsens barrel fouling, as it allows more places for soot and muck to build up. Compare the trouble you have to go to to clean a smoothbore shotgun barrel to the trouble of cleaning a rifle barrel.

At the very least, why go to the trouble of cutting the more complex spiral grooves when similar straight grooves would do the same job?

Need i remind you that "rifled musket" technology is prevalent to the early 1800's and the current year is 2008?

Need I remind you, the concept of steam locomotives is even older - and last time I checked, they still work...
Old technologies don't stop working because they've been surpassed.

Rifled muskets still work just fine. Just because they're not a .392 Remingchester Super-Blotto Magnum doesn't stop that.
Things do not move through the air different today to what they did 200 years ago, physics has not changed.

In fact, to head back to the earlier example, there was a Scrapheap Challenge (The UK's version of Junkyard Wars) to commemorate 200 years of rail travel, where the steam team actually won out to the diesel and electric teams - and although irrelevant here, it is in my opinion, the best episode of the show I ever saw.

The paintball is meant to be fired in quantity rather than quality

That doesn't mean it has to be. I mean, PVC pipe is meant for water and plumbing systems, but you'll seldom find someone using it for that on this site.
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Unread postAuthor: judgment_arms » Mon Apr 28, 2008 7:27 pm

The paintball is meant to be fired in quantity rather than quality

I missed that the first time; that makes as much sense as the guy at the paintball store that told me that “paintball guns are pistols, and you don’t aim a pistol you just point them”
And I pride my self in my one shot – one kill capability, I can hit a man sized target out to 30 yards 100% of the time, with my stock Tippmann 98c.

How come every time I bring up my paintball rifle project there’s always someone who has to make the argument that you can’t rifle a paintball…

Jimmy101, Ragnarok, thanks. :)
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Unread postAuthor: Ragnarok » Mon Apr 28, 2008 9:00 pm

“You don’t aim a pistol you just point them”

That's a really daft thing for anyone to say, and a very dangerous thought to entertain.

You know those light-gun games at arcades?
Most people go for Hollywood style shooting, which doesn't work very well. Now, if you use the crude attempts at "sights" attached to the light-guns (commonly pistols, although shotguns aren't too rare), hit rates will rocket...
I think my record on one of those things is just over one hundred consecutive hits - good for an extra life or so.

Arcade games are much better value when you know how to play them - especially on racing games when I get more extra time for reaching a checkpoint than it took me to get there from the last one.
I scare my driving instructor (yes, I have yet to take a test, Uni gets in the way)
You know, I suspect I may be a video game nerd. Now for an extra challenge, I need a light-gun driving game.

Jimmy101, Ragnarok, thanks :)

Always around to spout scientific jargon when it's needed. One point twentyone Jigawatts!!!
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Unread postAuthor: Lentamentalisk » Mon Apr 28, 2008 9:49 pm

Ragnarok wrote:One point twentyone Jigawatts!!!

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btw, its gigawats
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Unread postAuthor: judgment_arms » Mon Apr 28, 2008 9:55 pm

Lentamentalisk wrote:btw, its gigawats

But it was pronounced “jigawatts” in Back to the Future.

I don’t get the picture…
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Unread postAuthor: Lentamentalisk » Mon Apr 28, 2008 10:03 pm

He was referencing the 1.21 gigawats it would take to levitate a squirrel on a solar sail, as talked about in XKCD in their blag.
I highly suggest you read some of XKCD, it is the ultimate geek internet comic strip.
...now back on topic...

edit: I though he was referencing it at least...
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Unread postAuthor: judgment_arms » Mon Apr 28, 2008 10:08 pm

Lentamentalisk wrote:He was referencing the 1.21 gigawats it would take to levitate a squirrel on a solar sail, as talked about in XKCD in their blag.
I highly suggest you read some of XKCD, it is the ultimate geek internet comic strip.
...now back on topic...


1.21 jigawatts was originated by Back to the Future, and since me and him was just talkin’ ‘bout BTTF I figure that’s what he was talkin’ ‘bout…
Dang-nab-it, I’ve gone and started typing hill like, I needs to go to bed now…
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Unread postAuthor: Ragnarok » Tue Apr 29, 2008 4:55 am

I highly suggest you read some of XKCD, it is the ultimate geek internet comic strip.

I do indeed read XKCD, one of about 30 webcomics I read on a regular basis (I have read many more in the past, but most of those have finished).
...but here, I am quoting from Back to the future, around 23 years before the XKCD blag post - where it is pronounced as Jigawatts, albeit incorrectly.
If we're really breaking this down - it's pronounced "One point twenty one Jigawatts", it really should be "One point two one Gigawatts", as you can't consider decimal points like you would whole numbers.

Any time you see a quote of 1.21 Gigawatts, it's almost certainly a reference - if it's spelt Jigawatts, definitely.
For example - If you look at the introduction page to Google's calculator, one of the sample equations is "1.21 gigawatts/88 mph" - I think Google might just be run by total nerds.
88 mph, if you are unaware, was the speed the Delorean time machine needed to reach to travel through time. That often gets referenced to as well...

It's a good trilogy of films, you should see them if you haven't - there are dozens of subtle, and not so subtle nods to it even today.
Top Gear, although it wasn't done at 88 miles an hour, did a car roll stunt using the BTTF theme music and a rather deliberate editing style as the car was accelerating up to speed:
http://www.youtube.com/watch?v=hivbCfrNAH0
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Unread postAuthor: judgment_arms » Tue Apr 29, 2008 8:01 am

Ragnarok wrote:88 mph, if you are unaware, was the speed the Delorean time machine needed to reach to travel through time. That often gets referenced to as well...

Actually it’s 88.8 something miles per hour (if you want the exact number I’ll pop Back to the Future I in the VCR and find out), but they always shortened to 88mph.

I read some of that XKCD, found it as nerdy as it was funny, although, I’m proud to say, they lost me in a few of them…

Thanks Ragnarok, just when I had The Back to the Future Theme out of my head, you had to show me a video with it in it, now I’ll have to warm up the turntable and put Ma’s BTTF I sound track on…


Wow, I never realized how much BTTF memorabilia I had until now… heck, I’ve even got a scale model of the DeLorean from part III, the one with a working flux capacitor and Mr. Fusion, unfortunately the model of the city I had is not to scale… that’s three BTTF jokes in one sentence, GREAT SCOTT! :D:D:D
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