Internal diameter of extension tubes

[gstarik]

Yes,that's correct.
The Starik Carbon Tube (the one which Matt Emmons won WC Korea with) weights about 200gr depends on tube length.
Guy.

[patriot]

Bee Sting Carbon Fiber 1.118 OD & .850 ID

My Anschutz 1813 factory barrel bulge at the muzzle is slightly wider; friction fit would be an issue. The 1913 is consistent.

Mark

[markgrabowski]

From many tests and experiments,I can tell you that the minimum diameter of the inner tube should be more than 13mm.
Below that, accuracy goes down. All diameters above 13mm gave me the same results.
What really matters in my opinion,is the bloop tube weight. I have found out with Dr. Jeffrey Colbe(the previous owner of Border Barrels) that you can't tune for "positive compensation" if the weight of the tube is over 250gr.
Guy.

bump

[Albert T]

Guy,
Why does the smaller than 13mm give bad results? Is this because of gasses bouncing back and making a turbulence while the bullet passes through them? I can remember that Mike Eckhard many years ago designed a bloop-tube with an inner tube that was adjustable in the front-aft position in the main tube. It shielded the bullet from the turbulence. It was immediately banned by the ISSF!

Albert T
(The Netherlands)

[Thedrifter]

i would like to encourage the use of carbon fiber too. while i dont own one, i would like the beesting myself. its on my wish list.