Internal porting?

[confedman75]

would a barrel that is internally ported be more accurate than a barrel that is normally ported? by internally ported i mean pretend putting a hallow block around the ports so the air still goes foreword but not behind the ball, rather than going 90 degrees out of the barrel, like normal porting. The air(with internal porting)would exit in the same direction as the ball.

I was thinking it would be more accurate because the air would be still filling the vaccum behind the ball, for about a foot or two, after it leaves the barrel, the time when the ball is going its fastest.

what do you think or know?

[Top Secret]

Going to take a visual shot at what you are getting at.

==== <-- Outer barrel
---- <-- inner barrel

========================
------ ----- ----- ----- ----- ----- -----



------ ----- ----- ----- ----- ----- -----
========================

I'm curious as to the effects this would have as well, since the air is not just immediatly lost into the open air.

[ezrunner]

I can envision the machinery
needed to do this job, but I
am not sure of the benefits
of this design.

I think there would be turbulence generated behind the
ball. This could help lower the pressure behind the ball, what I
don't relly see, is how this would be better in any way than
standard venting?

Are you trying to slow down the air behind the ball instead of
lowering the pressure? That sounds like another way of
killing the same bird. But hey it may work.

-rob

[Crimson_Turkey]

That is a slinecer. It would make the gun more silent.

[confedman75]

to topsecret yes
and to crimson turky your right but i never thought fo that

[SlartyBartFast]

One way or another, the only thing porting does is make your marker quieter.

(and possibly make the barrel look cooler.:p )

[Crimson_Turkey]

Porting does have a huge effect on the way the ball flys. Get a stock barrel and add some porting to it. You will see the difference.

[hitech]

Originally posted by Crimson_Turkey
Get a stock barrel and add some porting to it. You will see the difference.

I have, and I did not notice any difference.

[SlartyBartFast]

Originally posted by Crimson_Turkey
Porting does have a huge effect on the way the ball flys. Get a stock barrel and add some porting to it. You will see the difference.

Doubt it. The difference will be the paint to bore match and surface finish of the barrel.

Take a ported barrel and tape up the holes. It might make it louder, but that's all. It may increase the muzzle velocity depending on the amount of porting.

[flanders]

wel if it's a silencer ur screwed i wouldn't make it unless u market it as a normal barrel don't talk alot about how quite it is

generally the silencer is an atatchment but i dun know sketchy idea cool

btw ud make it by haveing it in 2 piece have a normall barel porting then have threads so u can screw on the 2nd layer

[Vegeta]

THat is not how a silencer works. A silencer takes the air out the ports and filters it through carbon discs or stell wool. What you are proposing however I do not know hte side effects. I can say that it will cause some turbulence.

[Crimson_Turkey]

Some silencers (cheap ones) have no filling. They are only covered ports.

[poopthatkilledelvis]

Thats not how a silencer works. It works by allowing expanding gas to to exit the barrel slowly thru the porting into the outer casing (which will have a volume equal or greater than the insde barrel volume), and at the same time extinguishes the flame which also causes a cracking noise from super-heating the air around the exit of the barrel. And the gun must be shooting sub-sonic ammo, super-sonic ammo can't be silenced easily.

and IMHO porting in paintball dosen't affect accuracy, only sound signature. Palmer's Pursuit has been making unported brass barrels for years and they're considered some of the best. I swear by mine, loud as hell, but accurate.

[Crimson_Turkey]

I have a silenced A-5 barrel. I put a piece of pvc over the barrel and closed up both ends of the pipe. The porting on the barrel is all inside the silencer and im nice and quiet. Well not quiet, it's a a tippy.

[Trench]

I am dont see why you would do this, but it could be cool...

[paintposse]

the porting makes the gun very quite but lose air efficency but a barrrel with out any ports sounds like a shotgun. there is pressure behind the ball that pushes the ball forward. if there are no ports the ball would have a greater amout of pressure behind it longer. but at the end it would be loud becouse of the great amount of pressure relesases. with ports the air is gradually released creating less ad less pressure so the ball will slow down towards the end of the barrel but it will be quiet. With a parted barrel u would need to raise your volocity to balance the loss of pressure making ur gun suck up more gas. But a barrel without porting would sound like a mini pipe bomb. it has the same principle.

[athomas]

Using good paint and a good paint to barrel match, porting does not seem to have much affect other than reducing efficiency and providing a silencing effect. Most ported barrels that people use are step drilled. The barrel extension is actuall a larger bore than the breach area of the barrel. This extension is the part that is ported. It is the larger diameter in the barrel extension that is providing more stability to the ball than the porting that is drilled in it.

[314159]

Originally posted by athomas
It is the larger diameter in the barrel extension that is providing more stability to the ball than the porting that is drilled in it.

so a larger diamater tube for a paintball to shoot through is more accurate because it provides stability? that is like saying big bore barrels are more accurate because they provide more stability.

the 2nd stage of the barrel does not do much at all, (it adds a fraction of its lenght to the effective barrel length equilivant of an unported length of the barrel)

it can be hard to clean out a 2 stage barrel well on the field also.

[paintposse]

i tried it and it doesnt work. it makes the barrel pratically a barrel with no ports but with bad air efficency. What i didnt was that taped some cloth around my barrel and put a pvc pipe over that. It was practically somethin inbetween a ported and non ported barrel

[Mossman]

I couldn't imagine it could help anything

[athomas]

Originally posted by 314159


so a larger diamater tube for a paintball to shoot through is more accurate because it provides stability? that is like saying big bore barrels are more accurate because they provide more stability.

Not quite true. In the stepped barrels, the effective barrel length for propulsion is the first section that is tighter. This starts the ball on its way and must fit the ball to provide a stable flight. The larger stepped estension acts as a guide only to keep an already straight shot, straight.

If a barrel starts larger than the ball, the pressure can cause acceleration in many different directions that would cause wobble as the ball travelled down the barrel or can start a spin if the ball starts rolling down just one side of the barrel.

Once the ball gets moving in a straight line, it only needs a straight guide to hold it on its path. You actually want to remove any interference that would cause otherwise. Interference could be in the inconsistencies in the surface smoothness due to dirt or residue.

The extension bore size can't be too exaggerated either or it is useless. It must still provide function as an extension of the barrel to maintain acceleration on the ball.

[314159]

Originally posted by athomas
Not quite true. In the stepped barrels, the effective barrel length for propulsion is the first section that is tighter. This starts the ball on its way and must fit the ball to provide a stable flight. The larger stepped estension acts as a guide only to keep an already straight shot, straight.

effective length of a ported barrel, is the lenght of a non ported barrel, with the same inner diamiter, that will shoot at the same velocity. a 12 inch barrel, with 6 inches unported, and 6 inches ported would have a longer effective length than 6 inches. why? because the ball still accelerates a little bit in the ported section of the barrel.

and as far as what you are saying, if the ball is still acelerating, in a larger bore (2nd stage), how is this different from just shooting a ball in a large bore barrel?

[hitech]

Originally posted by 314159
...A 12 inch barrel, with 6 inches unported, and 6 inches ported would have a longer effective length than 6 inches. Why? Because the ball still accelerates a little bit in the ported section of the barrel...

Tom doesn't agree with you. Here is a quote from his tech tip:


It is simple to understand that the harder you push something the faster it will accelerate and get up to speed in a shorter distance. So what distance do we have to get the ball up to speed? The effective length of the barrel is from the balls position before it's fired, to the place in the barrel where the pressure gets released, This is usually at the first porting holes or the step in the barrel. Porting is there to release gas pressure!! You are effectively stopping the acceleration at the ports so your 14" barrel that is half full of holes only has an effective length of 7".

[SlartyBartFast]

Well Tom can be wrong you know.

I can here the cries from the villagers with the pitchforks now:
HERESY!! HERESY!! Out with the heathen!:D

The loss of pressure due to the porting isn't instantaneous so the ball will still experience some accelerating pressure. But Tom is probably mostly correct. WHen you look at it the majority of the acceleration of a ball happens in the first 3 inches anyways.

[314159]

hitech, then what would you call the aproximation of a ported barrels equilivant non ported barrel.

toms model is functional, but it is a first aproximation.

this model would be a second aproximation.

[athomas]

I have to agree with 314159 in that the ball will still accelerate some in the ported extension. How much depends on the porting which will dictate how much of the pressure is vented off and how quickly. You can check this by holding your hand over the end of a ported barrel and blowing into the breach end. You don't get much resistance. Now, start covering the holes along the barrel. As you cover more of the holes , you will start to notice more resistance. That means there is pressure available behind the ball to provide acceleration.


Back to my explaination of large bore extensions:

A ball reaches most of its velocity in the first 3 - 4 inches of barrel length. The remainder of the barrel just completes the acceleration to maximum velocity. In the first few inches, its also hard to impart a spin on the ball. Once the ball is in motion in a straight trajectory without spin or wobble, its path can't be easily altered unless it comes in contact with something. The larger bore extension can still provide a guide for the ball where the ball travels pushed by a cushion of air. The ball contact with the inside of the barrel is minimal so not much affect by contact to alter the trajectory. If a ball starts a spin in the first few inches it can't be maintained once the extension is reached because much of the force around the ball is equalized.

A barrel with the same bore throughout its length, works well if all factors are good. If any other factor starts a deflection, it may cause the ball to start spinning and will be maintained throught the remainder of the barrel. This just means that the rate of spin will accelerate as it travels down the barrel in contact with the sides of the barrel.

[hitech]

Originally posted by 314159
hitech, then what would you call the approximation of a ported barrels equivalent non ported barrel?

Are you asking what the effective length of a ported barrel is? I'm not sure what you mean by "the approximation of a ... equivalent". All other factors equal, a ported barrel will fire a paintball with slightly less velocity than a non ported barrel that is the same length as the non ported length of the ported barrel. At least that is what Tom is saying, and he is the only one I know who has tested his theories and "published" them. I'm buying it until someone can show him to be wrong.

[314159]

tom is saying that the effective lenght of a barrel is where the porting stops. i say that this is a first aproximation, because the ball still accelerates in the ported section.

a second aproximation, takes the ported section into effect, and would give you a lenght of an unported barrel, that would have the same velocity, and characteristics of the longer, ported barrel. this number is more usefull for calculations, but is also harder to get.

bolth of these numbers are the effective length of the barrel, it is just for most uses, the first aproximation is fine. i am shure that tom realises that, and so he will use that form when it suits the topic.



the point that i am trying to make, is that i am trying to make, is that i do not feel that ported barrels are more accurate than non ported barrels.

as far as 2 stage barrels, because the ball still accelerates in the second stage, it has a chance to be affected by the air accelerating it. because it has a larger bore, it would have the chance to bounce around (further testing is needed) or it could just fly straight. i think that if i wanted to stabolise a paintball, i would raither just have a barrel that would not let the ball wobble.

[confedman75]

the frames per second wasnt working quite right on my comp so i did 2 one realy fast and one realy slow(flash, gif)
its an anitmation that i whipped up showing how an internally ported barrel would remove vaccuum.
http://pro-mktg.com/MAIN/images/Untitled-1.htm

[athomas]

confedman75

At the end of the barrel when a ball exits, there isn't much excess air pressure behind the ball. The energy contained by the moving ball would be so much greater than the force of the air moving around it, that there would be no noticable deflection in the ball.

The point is you can't get enough air behind it to fill any vaccuum void if it did exist. If you did,it would be a waste of air and you would get terrible efficiency.

[SlartyBartFast]

There is no vacuum behind the ball unless your barrel is too long. If the barrel makes even the slightest 'pop' noise when a ball is fired it means there was pressure behind the ball.

Once the ball is free of the barrel, vacuum behind the ball is normal and unavoidable. Simple flow dynamics/air resistance.

[Kip Walker]

The only way this would help besides silencing the gun would be if you hoocked microline to the end of the horizontal ports out of the tip of the barrel and attached them so they would semi fill the air chamber before firing the next ball. ///
///
/-----------------\///
| o oooooooooooo o///
| o o//
| o o/
| o o|
| o oooooooooooo o|
\-----------------/

/= microline
o= horizontal ports