I don't see EITHER bench rest shooter HANGING A WEIGHT UNDER THEIR BARREL.I wish someone with a bow damper on their rifle to SHIFT IT 90* if the accuracy is still there..My point is/ most of the air rifle barrel are PREDRILLED. for the transfer port and no way to predict witch way the harmonic will be .. If it vibrate side to side, the hanging weight will act as a pendulum.Enough said for me.... It is very hard to explain something nobody want to hear.
Yes higher power shooting need reduce or adjust vibration especially at using light and long barrels.The question only is which is the easiest and also universal way :1. Barrel stiffening via CF tube2. Barrel stiffening and longitudinal tensioning via CF tube and nut3. Barrel fixing/tensioning to the air tube whit band may act the same as additional weight We only be sure that the air tube does not deforms by pressure changing.4. Adding heavy LDC5. Adding some extra fixed weight6. Adding some extra elastic weight(Harmonic DAMPER ? )7. If velocity is not absolutely stable we can tune it for particular distances via moving them. For now I only use 1 and 3 and I do not understand fully the different between 5 and 6. Why are you preferring number. 6 ?
Perhaps I am misunderstanding what you are trying to build.... but sliding a weight along the barrel is basically trying to change the harmonics so that the pellet arrives at the muzzle when it is pointing in a consistent direction.... In other words, you are tuning the barrel for a specific pellet and velocity, exactly what the rimfire benchrest shooters do.... This harmonic tuner I made does the same thing....The threaded steel sleeve is screwed onto the barrel and tightened in place.... The brass weight moves back and forth to tune the vibration of the barrel to your pellet and velocity.... It is 28 TPI, so it only moves 0.003" for each "hour" (30 deg.) you turn it.... I have not had the opportunity to do much testing, but I understand movements as small as 0.002-0.010" can make a big difference in group size, depending on the weight you are moving back and forth....The difference between moving a solid weight and using a mass of "lead slush" (or mercury) is that I think the latter would have a wider "sweet spot", and be less critical on placement.... The reason I suggest that, is that if with one pellet and velocity the barrel is not moving much, the damper effect would be small.... However, with another pellet and velocity, that is not shooting well because the barrel is whipping around, the damper should have more effect.... That, logically, to me would be why it seems to work better on improving "poor" bullets or pellets.... The moving shot "damps" the vibration, rather than "tuning" it to a given frequency like moving a solid weight does.... JMO....I have been giving more thought to the viscosity of the oil in the damper, and I think the "thinner" it is, the better.... We are dealing with a very short duration event here, the pellet is only in the barrel for about 3 mSec (0.003 sec.)…. At 850 fps, it travels the last 2" of the barrel in just 0.2 mSec.… As viscosity increases, the fluid takes longer to move for a given force applied to it.... Think about dropping a single #8 shot onto grease, heavy gear oil, light hydraulic fluid, or water.... It might take days for it to make a dent in the grease, a minute or more to drop an inch through the heavy gear oil, a second or two through the light hydraulic fluid, and almost no delay through the water, even though the water is more dense (ie oil or grease float on water)…. Mercury is probably the ideal fluid, because it is nearly twice as dense as lead shot (13.6 vs. 7.0), so the same weight takes up half the volume.... In addition, it's viscosity is only 1.5 (water being 1.0), whereas a light hydraulic oil (like the power steering fluid I used) is about 80, and 30W motor oil is about 350.... Simply put, for a given force applied, the lighter the oil, the faster the lead shot can respond to the barrel vibration.... and it doesn't have long to respond during the 0.0002 sec. it can affect the flight of the pellet.... Mercury can respond even faster.... Bob
Wow, the MAD Pipe* is picking up speed!! Awesome! *Mike's Accurizing Dampener Pipe
Quote from: JungleShooter on June 18, 2019, 09:18:36 PMWow, the MAD Pipe* is picking up speed!! Awesome! *Mike's Accurizing Dampener PipeCorrected term to remove implied use of water! Correct word is DAMPER!
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