Barrel Harmonics, the DEAD barrel?

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I think the barrel thing has three sides. Is it about accuracy, consistency or is it about the projectile. Most of us know that those soda straws are capable of some amazing accuracy. Especially with pellets. Remember guys, we are buying pellet guns and even now the so called slug shooters are still just pellet guns with a more optimistic slug shooting option. So if you are shooting pellets with insane accuracy out of your soda straw, the interest would be in a barrel that is consistent with its POI. You don’t need a dead barrel as much as you need one that securely mounted. Now onto slugs. These are the projectiles that truly expose a barrel and it’s weaknesses. I believe that when and if certain manufacturers sell a gun that is a true slug gun, they are going to have to rethink how they are approaching barrels. It may even be in their best interest to be caliber specific. If you want to pretend your airgun is a real gun, then build it like one. Personally I hope the slug airgun never goes completely mainstream. I don’t want kids or full grown buffoons shooting birds off wires and rooftops in neighborhoods. But that’s another topic. Once I get my leade and slug size dialed in, the biggest gain I saw with my TJ slug barrels was tricking them into thinking they were shorter than they actually are. Never had to do that with pellets.
 
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I’m really interested in tuning my barrels to the pellets vs. trying to find a pellet that my barrel likes? If this is truly possible in a airguns, which I believe is possible. This is basically what Rimfire Benchrest shooters do for different or changing lots of ammunition.

The dead barrel analogy may not have been the best to describe what I’m talking about, but have heard this phrase in different disciplines.

I understand barrels ‘vibrate’ or a have a harmonic signature regardless of dia.,Length, material. etc. but I believe this can be manipulated to give the best accuracy for a given projectile of different weights or design.

This becomes especially important when you’re limited to ftlb restrictions as most BR shooters are.

Please give examples of design and accuracy improvement good or bad! If you have experimented in this type of tuning.


 
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I don’t think you can compare tuning pellets to a barrel to a bullet. Weight is one factor but the bearing surface of each projectile is what separates them when it comes to tuning. Guys that are tuning 22’s have the same bearing surface with all bullets. With pellets we search for the right head diameter that jives with the waist and overall length. Pellets just don’t shake a barrel like a bullet.
 
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That’s exactly my point Vetmx, I think you can tune your barrel for a design of pellet and weight there is no proven science that says you can’t?

A barrel has vibration or harmonics no matter what projectile you use because hammer, valve, port air flow all contribute to this vibration.

If your a FX junkie they seem to think so as well, although personally I don’t see much merit in there execution of this, but time will tell and there design might prove to be a winner?
 
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There may be something to tuning a barrel with a pellet or maybe it’s just air delivery and velocity. I can shoot 3 different weight pellets out of my Dreamline if I slow each one down as I get lighter. And I shoot amazing 100yrd accuracy with just orings on the liner. But I think all the carbon fiber sleeves and barrel tensioning are focused around slug use. I never needed to stiffen things up for pellets but it makes slug life easier. Pellets are odd projectiles and I think they have their own set of tuning rules. For some reason I think if JSB’s group better than H&N’s out of a gun, you may be able to tighten the H&N’s up with some barrel tuning but they still won’t shoot better than the JSB. It’s probably not a barrel issue as much as it’s a which pellet design and composition likes your choke more. 
 
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Idk I think that might be wishful thinking. Still with Rimfire BR they don't necessarily just pick one bullet and just fiddle with a harmonic tuner to get it to shoot accurately. They try out all kinds of different ones, then lot testing then assuming they mess with a tuner after that. 

With pellets I still don't think you can just pick whatever pellet you want to shoot and make it work. Theres more to it than just harmonics. How the pellet and barrel fit each other is incredibly important. 

Case in point, let's say I wanted to get my gun to shoot the Original Monsters in .22 from JSB. I literally threw them in the trash they were so piss poor in all my guns. Like couldn't hit a 8x11 paper Everytime at 50yds. More like 6 out of 10 times if I was lucky. I don't think fiddling with any actual velocity tuning and then harmonic tuning with a harmonic tuner would make those guns shoot them very very well. I could be wrong but I just don't see it.

Now unless say you have 3-4 pellets that will all shoot fairly well out of a gun, and you wanted to pick one specific one to work with and mess with all the tuning harmonics to get that better than I think you could. But say any pellet you'd like? I don't think so. Not if it shot poorly from the get go.
 
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I think I haven’t fully explained or clarified what I’m trying to accomplish.

First I am personally not trying to make any pellet I choose into a match winning pellet, but as an example say my gun shoots pellet “A” extremely well, (maybe it grouped those the best it ever has) now I’ve shot all of that lot and bought more but for some reason they don’t group as well? Check for the normal inconsistency’s, weight, head size, damage etc. etc. no luck! ( Thank you JSB! )

Second, I have velocity constraints because of ftlb restrictions, this is where a tuner will or can bring that different lot of pellets back to the original lots accuracy? (Maybe a completely different Manufacturer’s pellet that shot well, but not as well!)

Third I’m not necessarily trying to make one gun shoot any pellet you pick off the shelf into a 100yd extreme Benchrest rifle winner, but guns that aren’t so easily tuned by velocities barrel length or even “different barrels for that matter”.

Let me say that I have a narrow window to shoot pellets accurately for my gun and discipline I use it for! This is where a “Barrel Tuner” comes into play.
This topic probably belongs in the Benchrest or field target sections, but wanted to reach out to a greater number of shooter’s that might skip by those sections? 
It’s a very, very deep worm hole indeed! 
 
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Nomojo... do you have a rifle in mind?

I ask this because the vibration cycle of the valve changes with the pressure of most, regardless of being regulated or not. It occurs to me that a sliding damper between the tube (if a tube gun) and the barrel would address both vibrations. Can't visualize how it could be done on a bottle gun in a fine way, but should be possible. I think RusBear - Nikolay, has spent some serious time on the barrel tuner and mentioned it in his EBR prize post and declines using it because it only tunes for 1 pressure /pellet weight /velocity combo. I've spent a small amount of time playing with the idea on several different rifles but in the end, just went back to basic config.

On the original 22 Monsters, I wonder if you really slowed them down, would they do better? The 177 original Monsters seem to do best going around 800 in rifles I've tried and are generally considered better than the Redesigns around this velocity. I'll try it, actually , and get back to you... nice to have a Heliboard for stuff like that.

Bob
 
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Is this a airgun forum? Not a center fire unlimited rail gun forum?, I just wanted thoughts and theories and experiences of “airgun harmonic tuners”. This subject intrigues me.

If I had machining skills I would experiment with more sophisticated types of tuners than I have been. For now I’ll have to make do with the rudimentary type.
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The pics @qball posted are totally relevant. Open discussions lead to new knowledge.
 
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Daisy 10meter gun. Single stroke pneumatic. Even at only 500fps in 177, if you move the front sight which is also a barrel weight you will change the poi and possibly the group size. It slides up and down the barrel with an inch or so of movement for fine tuning. 
 
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Daisy 10meter gun. Single stroke pneumatic. Even at only 500fps in 177, if you move the front sight which is also a barrel weight you will change the poi and possibly the group size. It slides up and down the barrel with an inch or so of movement for fine tuning.
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I have the exact same gun and it does NOT shoot well without the weight / sight. Great gun!!!

Mine was a CMP purchase and one of the best ever, money wise.
 
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I wonder if you could place a tight fitting cylindrical container of some kind on the barrel loosely filled with lead bb what would happen. Would the bb reduce or largely reduce the vibrations? If the barrel is blued the finish probably be damaged as the bb bounced arround.
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It has already been done. I designed one that doubles as an ldc and is known over on the GTA as The M.A.D. device. Or Mike Airgun Dampener. It is designed for slug shooters.

I didn't name it, the Forum did. Doesn't help pellet shooters much at all. But works wonders on high fpe slug shooters. s

Mike/Knife
 
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