Comments on Tight-Bore
One
I have experienced tighter groupings with JBU tight bores than with KM tight bores. And the team leader on my team, got the exclusive national distribution of JBU products. So I get them quite cheap. Besides, the KM is Ø6.04mm where the JBU is Ø6.03mm.
Two
the end. It seems to take out any rough spots and reduces alot of friction, prevents dirt and overall improves grouping by quite a bit in my tests so far. My best result was a 6,04 tightbore (brass) I polished, it has improved by awesome amounts.
I'll be re-crowing another test barrel and polishing it soon to see results. Hope that will be the difference.
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wolfdragon
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Re: Making any barrel a "tight-bore" barrel (the fine art of "choking.")
« Reply #3 on: January 06, 2008, 07:49:07 AM »
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Polishing the interior of a barrel OPENS it up, you are doing the exact opposite of choking… which yet again brings to light an important difference:
In real steel, the barrel is in contact with the bullet, thus why the bullet follows the rifling
Since we spin the ball at first, a reasonable seal is needed to keep the ball on course (and that punch of air behind it), but reduction of friction inside the barrel would be most advantageous to us because we NEED the backspin for stability, FPS is nothing if we cannot tell where the hell it is going to go…
Now heres a lesson (briefly) in how boundary layers occur in nature:
Consider a uniform flow of fluid (air or water) in a piper (barrel), at the center of the pipe the flow is at the uniform speed, as you move towards the wall of the pip, velocity of the flow decreases. This relationship is linear, exponential, or logarithmic depending on conditions. The important thing is, there is a measurable layer from the wall to where the local flow velocity is roughly 70% the velocity of the center of the pipe. This is called the boundary layer. This same layer exists around the bb, but since it has backspin, it is not a nice uniform shape like the bb (describing it would take too long).
Ever used a tightbore and noticed a significant DECREASE in performance?
That was because of boundary layer effects, the viscocity of the fluid changes in these areas and you get more drag, trying to cram the bb through the boundary layer of the barrel, as well as making the bb and barrel boundary layers interfere with each other causes an exponential spike in drag.
For this reason, some more open barrels are better than tighter barrels.
Now for the reality check, in our uses the boundary layers are no more than 0.25mm in thickness MAX (extreme ball parking here)
Polishing smooths the surface and helps reduce the thickness of the boundary layer, but if you are starting with too small of a barrel, you will still have problems
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Re: Making any barrel a "tight-bore" barrel (the fine art of "choking.")
« Reply #4 on: January 06, 2008, 07:53:55 AM »
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Quote from: Rob on January 06, 2008, 06:13:08 AM
I've already tried this with mixed results. I'll be re testing it soon with the addition below.
I'm finding moly polishing the barrel (in particular 6.04's) creates the best accuracy of all, so far. IMO
Interesting because I thought one of the advantages of tight bores was they were supposed to have more polished barrels…even "filled" a little from the manufacturing process. Maybe that is only true for the Madbull V2 Pythons.
http://www.madbullairsoft.com/English/index.php?main_page=product_info&products_id=57
It does make sense that polishing would help, though you'd have to go real slow as to not open up the barrel. Also you would want to be very careful not to damage the crown. In RS, they recommend never putting anything that can damage the barrel, like a cleaning rod, in from the end. They don't want anything to mess up the crown which can, in turn, really mess up accuracy.
What Moly product did you use? Do you have a link to the product?
Did find this Moly bore product at MidwayUSA.
http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=435941&t=11082005
One concern I would have is that any product is plastic/rubber compatible. Also wouldn't want to damage the hop or seals. Did you work on dissassembled barrel?
A heavy autowax….ideally synthetic, might work similarly. It would reduce friction and fill the voids.
Ideally you want as tight a barrel as will transport bb's reliably. Polishing, and lubing the barrel will allow tighter tolerances and lower friction.
Three
6.08 barrel - the height of accuracy. Discuss…
« on: November 24, 2007, 02:41:25 PM »
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Was about to buy a new tb barrel and was going for a 6.01 pdi - great reputation and had seen a fancy independant test somewhere that said a pdi had the 'roundest bore' so went on to x-fire and saw this…
High quality inner barrel.Its inner diameter is 6.08mm
This is new concep. Made of Stainless steel. It's not so tight,
This barrel keeps libration after trigger release low, and it rise up accuracy.
So had a little search around and found this quote
"Actually,we are not sure to say 6.04mm is the best barrel.
Because it's depend on each setting.For example,if you want better
FPS,we recommend 6.01.If you want better accuracy,you may choice
6.08mm.
In our opinion,
In case of smaller Dia.,youfll get more speed.
On the other hand,in case of larger Dia.,youfll get abetter accuracy.
Smalller Dia. has strong pressure for BB.An Airflow makes BB stable.
Thanks
PDI Co.,Ltd.
Sales Manager
Tomohiko Nishizono "
So what does anyone think. I was under the impression the tighter the bore the more accurate it was…
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MagnetoPenguino
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Re: 6.08 barrel - the height of accuracy. Discuss…
« Reply #1 on: November 24, 2007, 04:01:32 PM »
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That is an odd concept. The common concept is that a tighter barrel limits the "bouncing" of the bb inside the barrel, raising accuracy… I know the twist barrels are bigger (like 6.04 or something), but they have straight grooves inside it to stabilize the bb in the center, raising accuracy.
Isn't a stock barrel about 6.08? How would it be any better than that?
To expand on the topic, do you suppose a Twist barrel or a 6.01/6.03 would produce better accuracy in a P90 (stock length) at 380-390fps?
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Rob
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Re: 6.08 barrel - the height of accuracy. Discuss…
« Reply #2 on: November 25, 2007, 07:05:18 AM »
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From my own experience I found accuracy as well consistency goes u[ as the barrel size goes down.
So far the 6.03 have been best for me.
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hondo
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Re: 6.08 barrel - the height of accuracy. Discuss…
« Reply #3 on: November 25, 2007, 09:19:30 AM »
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Hi,
i also always thought that the smaller inner diameter the better the accuracy.
We here in germany have right at the moment an phenomenon about a cheapo
M500 spring-pumpgun which costs only 40 bucks.
This thing shoots with insane good accuracy at 70 yards,this thing has no tighbore at all,
no brass innerbarrel just a kinda look crap aluminium innerbarrel which is all but no tightbore super
dupa 100$ barrel.
I chronoed this cheapo M500 Pumpgun at about 292fps @ 0,23g BB-weight,which is only 0,9 Joules.
What to see is,that the fps are very consistent with very little spread.
I discussed this magic about this 40$ gun in many forums and got reply that plenty who have this gun too,that i am right with my results.
About an week ago we played in France and we had 2 of this M500 springers with us and i had the best experience with this cheapo got many kills at 50 yards and more.
We showed this amazing performance to the experts at the field and they couldn't believe it.
We tested against upgraded AEG's with tighbore's and they couldn't reach the accuracy of the 40$ Pumpgun.
I have the G&G-M14(1,4J) which was by the way my most accurate AEG and my M15(1,6J) with KM-Head tighbore didn't reach the precision the M500 Pumpgun has.
One already good known player here in germany(airsoft-grandpa) says this about tighbores:
The BB needs some space around it in the barrel to retain the spin given by the Hop-Up.
If we shorten this space between(what a tighbore does) the danger gets higher that the BB
looses this air-cushion(above and/or under the BB) and could loose an amount of the initial spin the HU has given,thats the tiniest part,
but if the space between is still more (extreme tighbores 6.01mm) the air-cushion could completely break and the BB would touch the
walls of the inner-barrel and could get a rocking motion…then not every shot has the same amount of HU-Spin given which resists in bad repeatability.
I now see the precision thing in a whole new light,
i think the precision comes with very constant fps shots which only spread very little,as measured in the M500 spring-shotgun.
I dind't think a tighbore will give the desired results a player bought for expensive.
This cheap Pumpgun with this Alu-inner-barrel which costs maybe about 1 dollar shows the difference…
greetings:
Michael
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Re: 6.08 barrel - the height of accuracy. Discuss…
« Reply #4 on: November 26, 2007, 09:42:29 PM »
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The main ingredients for good consistency are good ammo, hop-up, and straight/smooth barrel. Depending on the BB one uses, tightbore barrels can increase or decrease performance. If the barrel spacing is too tight for the BB, it can induce additional friction, which decreases the muzzle energy and disrupts the BB backspin. If the barrel spacing is too loose for the BB, it creates excessive airleaks and turbulence, which also reduce the muzzle energy and disrupt BB backspin. The simplest way to find a good match is to just try different BBs until you find a make that works well with your setup. Spending all that money on tune-ups but going cheap on the ammunition is just not right. Wink
BBs always bounce inside the barrel at the beginning. There's no way around it. (Happens even with the TK hop-twist barrels, but the resultant air vortex supposedly centers round quickly.) When a BB is chambered and launched, its direction vector is never straight forward, which causes the bounce. The BB's imperfections, the initial position of the round, the push from the nozzle, the friction from entering the barrel, the push from the air pressure, etc, can all influence the BB's initial direction vector. However, with the help of the hop-up mechanism, the BB's initial direction vector is essentially "reset." The imparted backspin creates an upward bias for the BB. Accordingly, the BB tends to roll on the top side of the barrel by the time it reaches the muzzle, with the air escaping and cushioning from the bottom side. Quality hop-up components can consistently impart the same (or close enough) spin every time.
IMHO, as long as a barrel is straight and smooth, there is likely a BB make that'd work well with it. Finding a good combo with the 3 ingredients is the main challenge. Tongue
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Re: 6.08 barrel - the height of accuracy. Discuss…
« Reply #5 on: November 27, 2007, 05:10:40 PM »
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bb's do have a huge impact on performance. I play on a very large 99acre field with wide open areas. accuracy is a must. The guys that have the dee's 6.01's have more range and very consistent accuracy. one guy runs a Systema complete mechbox and motor and with his 300mm inner barrel he outranges some sniper riffles with remarkable consistency for 32RPS!!! so it really is a matter of just experimenting and getting it right for your setup.I must say that the Dee's and the Prometheus seem to be the longest lasting for the tighter inner barrels
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Re: 6.08 barrel - the height of accuracy. Discuss…
« Reply #6 on: November 27, 2007, 06:06:41 PM »
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I was going to drop a dee's 6.01 in my P90 (stock length), but now I'm considering the twist barrel. does anyone have first hand experience with it running something like an m120 or guarder sp110?
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AnakChan
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Re: 6.08 barrel - the height of accuracy. Discuss…
« Reply #7 on: November 27, 2007, 09:39:54 PM »
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I've got a both PDI 6.01mm (not DBC) and Tanio Koba's Twist barrel for my P90. To be honest, I won't say one is better than the other (but the 6.01mm does result in slightly higher FPS naturally. the TK Twist is more for 1J and under as a way of getting accuracy without the violating JP regulations.
However, from reading reports from others about their TK's, results are inconsistent from report to report. So IMHO for a more "guaranteed" result, go with 6.01mm - use good BB's naturally :p.
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Re: 6.08 barrel - the height of accuracy. Discuss…
« Reply #8 on: December 03, 2007, 08:28:46 PM »
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I have a ton of guns g36,3 m4,2 mp5,4 famas,1 ak,3 ect. The stock TM Ak plus m120 is hard to beat do not know why but it beats a full upgraded g36 with prometheus barrel and boreup systema ect the good stuff. All though the g36 will last longer the TM AK will take worse ammo and shoot better. Undecided And I got 150 in the AK that sucks!!!!!
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Re: 6.08 barrel - the height of accuracy. Discuss…
« Reply #9 on: December 04, 2007, 09:50:35 PM »
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the TK "twist barrel" is designed to be used with stock gun(280~330fps) in conjunction it simply has straight grooves that "cushion the bb" reducing friction and making the backspin from the hop-up more effective.
Good at any velocity:
the Prometheus is for those who want to compromise between ultimate tightness and some free space.
the Dee's and other 6.01mm inner barrels are for those who are dedicated enough to use only the best ammo and to maintain its cleanness.
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eel one
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Re: 6.08 barrel - the height of accuracy. Discuss…
« Reply #10 on: December 05, 2007, 03:04:23 AM »
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What do you mean by "straight grooves". When you see the barrel it isn't straight but twists:
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Re: 6.08 barrel - the height of accuracy. Discuss…
« Reply #11 on: April 02, 2008, 08:47:59 PM »
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Has anyone tried one of the 6.08's yet?
I'm really curious to see if they hold up to the claims.
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bruin757
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Re: 6.08 barrel - the height of accuracy. Discuss…
« Reply #12 on: April 03, 2008, 05:35:48 AM »
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Just to throw another wrench in this discussion, I wonder what the impact is of BB weight on how much it bounces and when it stabilizes in the barrel. Will a .3g stabilize faster after the HU than a .2g? I would think that especially with the Twist barrels, when and where it stabilizes in the barrel would make a significance difference in performance.
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Re: 6.08 barrel - the height of accuracy. Discuss…
« Reply #13 on: April 03, 2008, 10:58:09 PM »
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Quote from: RiotSC on November 26, 2007, 09:42:29 PM
[…]
BBs always bounce inside the barrel at the beginning. There's no way around it. (Happens even with the TK hop-twist barrels, but the resultant air vortex supposedly centers round quickly.)
[…]
I'm not sure if it's just the JBU 6.03 mm aluminum barrel, but my team mates and I get a lot of junk after only a couple of thousand rounds using TSD BBs exclusively:
It seems that the BBs are not only touching the barrel at the beginning but till the end!
Anyone else made the same observation? Maybe there's even more gunk with 6.01 mm? Maybe 6.08 mm is more precise over a long period of time for example for support gunners (using a SAW or so)?
