Question for all F Standard shooters.

[Tony Z]

The barrels i have played with over the last ten years or so that have had tubes fitted have all shown the same traits. The best group out of the gun with no tube was attained almost at all times once the tube was fitted. The only real change was as the velocity picked up, so did the impact point climb on the target.
One thing i have recently learned is that those calibers that use bullets with very long bearing lengths like 6 and 6.5 mil seem not to show the same vertical flyers associated with these calibers in barrels without tubes. I believe the reason for this is the amplitude of vibration of a barrel with a tube fitted is greatly decreased. So as the barrel without a tube changes direction during vibration, this amplitude flings the tail of the base of the bullet if it is still partly in the bore. Now this is just my reckoning and to date i have no way to prove it. Shorten the bullets bearing length and the vertical vanishes even though the spin RPM is still present or indeed increased if the bullet is lighter and faster. We have currently got one guy up here shooting identical barrels in the same cartridge using the same bullet with the exception of one barrel being fitted with a tube. There is a distinct difference from what i am seeing in vertical dispersion. He is keeping logs and plots of both barrels to see what the final outcome will be, but from what i have seen so far, the tube has it. The caliber is 6.5 using 139 Scenars and 140 Bergers.

Tony Z.