I know rimfire enthusiests use barrel weights to "harmonically" tune their rifle barrels. Anyone got experience with tuning airguns that way?
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Harmonic tuning using barrel weights
- Thread starter jmoss80917
- Start date
I use these brass weights that I slide around. They are inside the shroud. Works like a charm!
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Add weight at the beginning of the barrel.
it would reduce harmonics movement effect. But frequency will increase. add your weight gradually or waves cut in two part. High at first then reduce it until half of barrel length.
it would reduce harmonics movement effect. But frequency will increase. add your weight gradually or waves cut in two part. High at first then reduce it until half of barrel length.
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A .22LR has 17,000psi peak chamber pressure. More than a .45acp. This should put into perspective what it takes to send smaller projectiles at even near supersonic speeds. Now .22LR competition shooters & AG’s also know to keep them well below 1100fps
Before I waste my time & yours, do you have a lathe? Any limits on what you wish to spend?
Are you seeing inaccuracies? I’m just wondering if harmonics are even an issue at unknown power, barrel, projectile weight & speed.
You could change harmonics by fitting a carbon fiber sleeve over your barrel, or adding a thimble to breech to test in rotating it while keeping flow through transfer port.
Before I waste my time & yours, do you have a lathe? Any limits on what you wish to spend?
Are you seeing inaccuracies? I’m just wondering if harmonics are even an issue at unknown power, barrel, projectile weight & speed.
You could change harmonics by fitting a carbon fiber sleeve over your barrel, or adding a thimble to breech to test in rotating it while keeping flow through transfer port.
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Hi James, thanks for responding.
I do not have a lathe and I'm retired (read poor). I've recently managed to scrape together enough to buy a Dreamline and mount a reasonably decent scope (Optisan Taipan) on it. But I'm not seeing the performance I know the gun is capable of. Part of it is undoubtedly me, but I think I need to find a harmonic tune for the gun too.
As I understand it, Harmonic tuning is adjusting the speed of the pellet/slug to leave the barrel on a resonance node (of the barrel). Bob O described his process on his Impact as doing a velocity tune and then fine tuning the muzzle velocity using the valve stop adjustment until you find the point at which the projectile leaves the barrel at a resonance node. Well and good, except my Dreamline does not have a valve stop adjuster. So I'm looking into changing the resonance of the barrel, with barrel weights, to adjust the resonance node to the time the projectile leaves the barrel. What I was hoping for was to find out where I can buy barrel weights, or do I have to have them made?
I do not have a lathe and I'm retired (read poor). I've recently managed to scrape together enough to buy a Dreamline and mount a reasonably decent scope (Optisan Taipan) on it. But I'm not seeing the performance I know the gun is capable of. Part of it is undoubtedly me, but I think I need to find a harmonic tune for the gun too.
As I understand it, Harmonic tuning is adjusting the speed of the pellet/slug to leave the barrel on a resonance node (of the barrel). Bob O described his process on his Impact as doing a velocity tune and then fine tuning the muzzle velocity using the valve stop adjustment until you find the point at which the projectile leaves the barrel at a resonance node. Well and good, except my Dreamline does not have a valve stop adjuster. So I'm looking into changing the resonance of the barrel, with barrel weights, to adjust the resonance node to the time the projectile leaves the barrel. What I was hoping for was to find out where I can buy barrel weights, or do I have to have them made?
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@jmoss80917 if all else fails the local hardware store usually has a section in it with brass bushings and the like. You can probably get one real close to the size you need. Then, with a hack saw, file, and power hand drill, you can make the weights you want fairly quickly by drilling the inside of the bushing to the barrel diameter so it is a fairly tight friction fit, cutting them to the length you desire, filing down the outside diameter, and even make an o-ring groove if necessary. Also, order a small bottle of Vibra-TITE 213 VC-3 Threadmate to position the weights here you want them to stay once you've completed harmonics tuning testing.
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Very long read! And Knife doesn't give details until later on in the thread. Results are hard to argue with though.
www.gatewaytoairguns.org/GTA/index.php?topic=157680.0
www.gatewaytoairguns.org/GTA/index.php?topic=157680.0
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Before adding barrel weights I would experiment with pellet speed, each gun has its sweet spot, a few fps can make a big difference.
Bb
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