Barrel Diameter Comparison

I am new to airsoft so i dont understand everything about the guns yet, but I am confused at the number of barrel diameters out there. Is it true that the tighter the barrel the more accurate the gun, that would make sense but the bulk of what i have read here and in other forums seem to point to barrel smoothness being the biggest factor in performance. Has anyone done an experiment to find out, or is it more person preference and experience with individual guns?

Alot of it depends on the quality of the barrel itself. The three best brands from what Ive heard are:

1. PDI
2. EdGi
3. Prometheus

PDI and EdGi make barrels in 6.01, while Prommy only goes down to 6.03, but Ive had excellent experience with Prommy 6.03s.

Edgi also does a 6.00, and there has been 5.99 before. There is huge amounts of debate about the effectivness of barrel inner diameter, especially now about polishing 6.05+ vs. tight bore. I am a strong opponent against the polishing larger diameter, the physics that they use to support it are just not logical to me.

there has been 5.96 but it is a custom barrel, they are not sold to the public yet. But I did a test on barrels search the forum and you will find it.

This experiment is interesting. http://airsoft-barracks.com/page.php?91

and i completely agree with you njsc on this one. The physics about a cushion of air forming around the bb make no sense. The tighter diameter barrels however make perfect sense and that is what is used on real steel.

https://metroatlantaairsoft.darkbb.com/upgrades-and-accessories-f9/this-is-huge-comparing-601mm-tightbore-to-a-608mm-stock-barrel-polishing-your-barrel-for-more-accuracy-t264.htm?highlight=barrel+comparison

Here is my link.

And a quote from the link posted before mine.

"Of course, I am left to wonder why a 6.03mm barrel would have better accuracy than a 6.01mm barrel."

So all the people who did not think my data was correct, here is a guy the had his gun steadied by a tripod for minimal gun movement and he got the same results.

I don't mean to crap you thread but there is and will probably always be a battle between barrel tightness and accuracy.

iv read through that several times and it is what really got me thinkin about the barrel question. That is excellent work on the comparison. Did the smaller than 6mm barrels have rifling in them?

maverick wrote:iv read through that several times and it is what really got me thinkin about the barrel question. That is excellent work on the comparison. Did the smaller than 6mm barrels have rifling in them?

No only Tonia Kobi??? I think thats what they are called, have rifiling in them and thay are only good to 350 fps, but no none of my barrels or the 5.96mm barrel had rifiling

Rifling in the true sense of its purpose to give a projectile spin around its axis parallel to its path wont give a round bb more accuracy, it has the opposite effect of making the bb curve left or right out of your barrel. And in my testing of a 6.01 Pdi and a 6.03 Prometheus the 6.03 was far more accurate at distance. You may not believe the cushion of air talk but with just classical physics you can't really understand it you need to understand fluid dynamics to grasp the idea but that is a whole other topic.

I "THINK" tight bores are a waste of money!

Zero wrote:Rifling in the true sense of its purpose to give a projectile spin around its axis parallel to its path wont give a round bb more accuracy, it has the opposite effect of making the bb curve left or right out of your barrel. And in my testing of a 6.01 Pdi and a 6.03 Prometheus the 6.03 was far more accurate at distance. You may not believe the cushion of air talk but with just classical physics you can't really understand it you need to understand fluid dynamics to grasp the idea but that is a whole other topic.

While you are correct in saying that you need an extensive knowledge in fluid dynamics to completely understand the theory behind the air cushion, this does not mean that the theory works in practical applications. Neither does it mean that it would not work though. I have a basic knowledge of fluid dynamics, but am unfamiliar with the theory behind an air cushion forming around the BB. Frankly, I do not see why it couldn't work though. If someone has a link to a post explaining that theory, I would like to read it.

Rhino wrote:I "THINK" tight bores are a waste of money!

WOW! That's unexpected............. can you explain?

Spectre wrote:

Zero wrote:Rifling in the true sense of its purpose to give a projectile spin around its axis parallel to its path wont give a round bb more accuracy, it has the opposite effect of making the bb curve left or right out of your barrel. And in my testing of a 6.01 Pdi and a 6.03 Prometheus the 6.03 was far more accurate at distance. You may not believe the cushion of air talk but with just classical physics you can't really understand it you need to understand fluid dynamics to grasp the idea but that is a whole other topic.

While you are correct in saying that you need an extensive knowledge in fluid dynamics to completely understand the theory behind the air cushion, this does not mean that the theory works in practical applications. Neither does it mean that it would not work though. I have a basic knowledge of fluid dynamics, but am unfamiliar with the theory behind an air cushion forming around the BB. Frankly, I do not see why it couldn't work though. If someone has a link to a post explaining that theory, I would like to read it.

But if you have one iota of stronger pressure in any direction e.g. hop up effect then it's just going to rattle down the barrel. That's just my guess. BTW completely off topic but hilarious, I thought your sig said "Paul is pain leaving the body"

Spectre wrote:

Zero wrote:Rifling in the true sense of its purpose to give a projectile spin around its axis parallel to its path wont give a round bb more accuracy, it has the opposite effect of making the bb curve left or right out of your barrel. And in my testing of a 6.01 Pdi and a 6.03 Prometheus the 6.03 was far more accurate at distance. You may not believe the cushion of air talk but with just classical physics you can't really understand it you need to understand fluid dynamics to grasp the idea but that is a whole other topic.

While you are correct in saying that you need an extensive knowledge in fluid dynamics to completely understand the theory behind the air cushion, this does not mean that the theory works in practical applications. Neither does it mean that it would not work though. I have a basic knowledge of fluid dynamics, but am unfamiliar with the theory behind an air cushion forming around the BB. Frankly, I do not see why it couldn't work though. If someone has a link to a post explaining that theory, I would like to read it.

I don't have a specific link to explain it but you could look up stuff about boundary layer theory and/or couette flow.

NJSC: while your right in thinking the pressure would cause the bb to rattle down the barrel. The presense of boundary layers against the barrel wall (also called the cushion of air in earlier discussions)has stabilizing pressure effects that inhibits the bb from just bouncing around.

Zero wrote:

Spectre wrote:

Zero wrote:Rifling in the true sense of its purpose to give a projectile spin around its axis parallel to its path wont give a round bb more accuracy, it has the opposite effect of making the bb curve left or right out of your barrel. And in my testing of a 6.01 Pdi and a 6.03 Prometheus the 6.03 was far more accurate at distance. You may not believe the cushion of air talk but with just classical physics you can't really understand it you need to understand fluid dynamics to grasp the idea but that is a whole other topic.

While you are correct in saying that you need an extensive knowledge in fluid dynamics to completely understand the theory behind the air cushion, this does not mean that the theory works in practical applications. Neither does it mean that it would not work though. I have a basic knowledge of fluid dynamics, but am unfamiliar with the theory behind an air cushion forming around the BB. Frankly, I do not see why it couldn't work though. If someone has a link to a post explaining that theory, I would like to read it.

I don't have a specific link to explain it but you could look up stuff about boundary layer theory and/or couette flow.

NJSC: while your right in thinking the pressure would cause the bb to rattle down the barrel. The presense of boundary layers against the barrel wall (also called the cushion of air in earlier discussions)has stabilizing pressure effects that inhibits the bb from just bouncing around.

Thanks, that makes a bit more sense now.

No problem glad to see all this time at Tech hasn't gone to waste.

I'm interested in Rhino's opinion on this, in terms of the "THINK" they are a waste of money. How so? I know you have a ot of experience with all kinds of airsoft guns and upgrades, so I definitly want to hear your two cents on the whole thing...

Zero wrote:No problem glad to see all this time at Tech hasn't gone to waste.

Haha, no doubt. At least you gained something from it, right? lol

I agree with you to a certain extent about the boundary layer of air zero, while the bouncing will be diminished it is still there. Also this layer of air will never be able to stabilize the projectile as much as solid contact with steel. I would like to here Rhino's reasoning on tightbores being a waste of money.

maverick wrote:I agree with you to a certain extent about the boundary layer of air zero, while the bouncing will be diminished it is still there. Also this layer of air will never be able to stabilize the projectile as much as solid contact with steel. I would like to here Rhino's reasoning on tightbores being a waste of money.

QFT

Well I don't think we want solid contact, because we would then have ~5.96 and bb's aren't completely uniform. In a perfect airsoft world, every bb would be perfect and we'd have the perfect inner diameter of barrel. But then one speck of dirt and JAM! IMHO tbb do not only improve accuracy, but also fps (with no stress on the gearbox) and range

One thing worth pointing out is that the discusion of flow around the bb is assuming that the surface of barrel is perfectly smooth. Polishing the inside of a barrel would improve the flows consistency generating more accuracy, but I still believe (perhaps incorrectly) that the tighter the bore the more accurate the gun will be.

That's what a big part of the argument is, if you polish your normal barrel, then you will get better results. There not been any "scientific" tests done of this yet. Several barrels, several guns, consistent variables, etc. all need to be taken into effect.

Yes and no njsc. Barrels on real steel are actually smaller in diameter than their projectiles. They handle bits of dirt and other debris in them all the time. Bullets are not perfectly round either but the accuracy firearms generate far surpasses that of airsoft. A lot of that cant be recreated because of the higher pressures and velocities but I would think that the principles in play would still apply. That being said a barrel tight enough to consistently contact the bb would be best for accuracy but it would actually hurt velocity because of the increased friction of the bb contacting the barrel.

it's comparing apples to oranges. There are astronomical differences, not just in terms of velocity, but also even as basic as shape of the projectile and the fact we use hop up.