Just a little excerpt from Cardew and Cardews book, "The Airgun From Trigger to Target," that I find interesting in the current atmosphere of harmonic tuners and carbon fiber tubing/epoxy situations.
Chapter 9-The Barrel
Barrel Vibration
"In the field of firearms, barrel vibration is often blamed for inaccuracy. High speed photography has been used to examine this phenomenon and shows that a rifle barrel vibrates and wriggles about like an excited snake as the bullet travels along it. This is not surprising when one considers the huge pressures generated by the burning propellant as it forces the tight fitting bullet along the tube.
We investigated barrel vibration to see if it was the cause of inaccuracy in airguns. We were interested only in vibrations caused by the pellet itself while it was in the barrel and we did not want to be concerned with any vibrations set up by a spring and piston so we used our pneumatic projector (a very solidly mounted pneumatic rifle whose barrel may be left unsupported over the majority of its length).
We mounted vibration transducers on the muzzle of a breech mounted barrel so that ay vibration would be picked up and displayed on an oscilloscope. A slight thump with a hand anywhere on the barrel would cause the trace to move violently, yet firing the gun produced very little reaction. By causing the pellet to break a circuit carried by a pencil lead as it left the barrel, we could determine whether the small amount of vibration we had seen occurred before or after the pellet had left them muzzle.
This experiment showed an insignificant amount of vibration before the pellet left, but that the small amount of movement we had seen occurred after the pellet had left. This after exit vibration could have no effect on the accuracy of the shot.
Various other experiments were embarked upon to cross check the first, also to assure ourselves that vibration played no part in the production of large groups. In one instance we clamped a heavy lathe chuck on the muzzle, on another occasion we mounted the barrel in soft rubber rings, but the effect on the group sizes was negligible. The important factor always appeared to be the combination of barrel and pellet, later on we realized that in fact the combination of pellet, barrel and velocity have a far greater influence on the size of the group than any amount of vibration from a rifle in good condition."
The copy I just quoted from is copyright 1995 so this was back when true solid barrels were the only thing being used. A potential caveat is that no mention of fpe is made.
Chapter 9-The Barrel
Barrel Vibration
"In the field of firearms, barrel vibration is often blamed for inaccuracy. High speed photography has been used to examine this phenomenon and shows that a rifle barrel vibrates and wriggles about like an excited snake as the bullet travels along it. This is not surprising when one considers the huge pressures generated by the burning propellant as it forces the tight fitting bullet along the tube.
We investigated barrel vibration to see if it was the cause of inaccuracy in airguns. We were interested only in vibrations caused by the pellet itself while it was in the barrel and we did not want to be concerned with any vibrations set up by a spring and piston so we used our pneumatic projector (a very solidly mounted pneumatic rifle whose barrel may be left unsupported over the majority of its length).
We mounted vibration transducers on the muzzle of a breech mounted barrel so that ay vibration would be picked up and displayed on an oscilloscope. A slight thump with a hand anywhere on the barrel would cause the trace to move violently, yet firing the gun produced very little reaction. By causing the pellet to break a circuit carried by a pencil lead as it left the barrel, we could determine whether the small amount of vibration we had seen occurred before or after the pellet had left them muzzle.
This experiment showed an insignificant amount of vibration before the pellet left, but that the small amount of movement we had seen occurred after the pellet had left. This after exit vibration could have no effect on the accuracy of the shot.
Various other experiments were embarked upon to cross check the first, also to assure ourselves that vibration played no part in the production of large groups. In one instance we clamped a heavy lathe chuck on the muzzle, on another occasion we mounted the barrel in soft rubber rings, but the effect on the group sizes was negligible. The important factor always appeared to be the combination of barrel and pellet, later on we realized that in fact the combination of pellet, barrel and velocity have a far greater influence on the size of the group than any amount of vibration from a rifle in good condition."
The copy I just quoted from is copyright 1995 so this was back when true solid barrels were the only thing being used. A potential caveat is that no mention of fpe is made.
