Big post 14... anyhow
**This is a proposal**
Intro
If your not familiar with the Tanio Koba twist barrels yet, they are 'rifled' barrels that create an air-cushion around a BB to create a more predictable and stable trajectory of a BB out of the barrel. (http://www.airsoftforum.com/board/Tanio-Koba-Twist-Rifled-B-t147334.html for more information) The only problem with the Tanio Koba (TK) twist barrels is that they are only effective up to 1 Joule. Please note, a joule is the SI standard for ENERGY- that means a .2g BB traveling at 100m/s has the same ENERGY as a .3g BB traveling at ~82m/s. (You can calculate other BB velocities and what not using the kinetic energy equation - KE= .5MV² The idea behind this experiment would be an attempt to derive what are the driving factors that make a TK barrel effective and use it to create barrels for higher FPS ranges.
I say a range of FPS, because clearly, there must be a lower end to a TK barrels effectiveness.
Set-up
First thing needed is an AEG with a reliable internals that can willingly take anything from an M80 to an M150 with a Type 0 cylinder. I was thinking an ARES would be suitable because it meets the requirements and has a quick spring change design. (I'm sure tearing down a gearbox after every test would affect consistency).
Next thing would be an actual TK twist barrel and at least 2 tightbore barrels (TBB) of the same inner diameter (ID).
And access to a reamer... which is my only problem here...
Measurements
First things first, what I will now call the 'twist ratio' would have to measured from an original TK barrel. 1 twist : _ _ mm. And another thought- do all of the TK barrels have the same 'twist ratio'?
Muzzle velocity would be measured from all of the barrels to get a baseline (Sample size between 10 and 20 shots)
Measure maximum range with the hop-up off. I argue with the hop-up off because a hop-up will decrease consistency regardless of which one you swear by- that way another factor is removed and doesn't need to be worried about.
Equations
Kinetic Energy: KE=.5mv²
Twist proportion: 1/t= kv
-Please not that 'k' is an experimental constant that will have to be derived from experimental data (units of sec/1000mm). I figured there was an inversely proportional relationship between the twist ratio (t- lenght of 1 twist) and the muzzle velocity. *Other ideas and input are welcome for debate here*
Data Table
Formatting will probably destroy this, but I'm going to try anyhow...
Barrel--------------Twist Ratio-------Muzzle Velocity (m/s)-----Range (m)
TK------------------1: _ _ mm
TBB_{1 & 2}
TBB₁ w/ mod----1: _ _ mm
TBB₂ w/ mod----1: _ _ mm
Modifications would be up to the user AFTER getting 'k' in the twist proportion equation.
Miscellaneous
What is the lower end of a TK barrel's effectiveness? This would greatly help in calculating the range of velocities other twist ratios may be used for.
-This could be done through trial and error, slowly scaling down the FPS until the TK barrel matches the range of a similar ID TBB.
Other factors that I did not mention: Groove shape (curved vs. edged), groove dimensions, and number of grooves.
This test would assume that the TK barrel has the most effective set-up with all of the previously listed factors and use the same groove dimensions for the sake of practicality.
Decreasing the number of grooves would decrease the number of points of contact with the barrel and possibly increase predictability.
0.2g BB would be used throughout.

Okay, since all the thinking is done, I hope that someone with access to a reamer can do something more with this.
Anything put up here is open to discussion and constructive criticism.
EDIT: Forgot to define Range, this would be the maximum range- when the BB hits the ground. This can be done from any height you want to, therefore benchrest shooting is good.
Range woud be measure in %.
Equation: (Range_measured - Range _theoretical)/ Range _theoretical * 100%
- Positive gains in range would be denoted by +% and the opposite for decreases.
- Range can be calculated using 2D Particle Kinematics
Range_theoretical= v_o(h/4.9)
-h denotes height from ground to the center of the barrel
And I entirely forgot about an accuracy test. That is pretty self-explanatory, but still is needed.

This post has been edited by Frosty23: Dec 7 2010, 11:54 PM