"Ghetto" Harmonic Barrel Tuner

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SkeeterHawk

SkeeterHawk

Member
Oct 23, 2021
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Florissant, Colorado, United States
Hello again, Shooting Enthusiasts!

I'm still trying to get my feet on the ground after returning from RMAC, and one thing that I wanted to do was to talk about the "ghetto" harmonic barrel tuner that I was using at the event. I got asked about it a number of times, so I thought I should just post it here.

In short, this is something that I threw together the week before RMAC as a quick test or proof of concept, and it made such a huge difference that I went ahead and left it on there for the competition.

20220609_084637.jpg

This is the basic concept. It is just a clamping Picatinny rail clamped onto the Donny Adapter on my Avenger. I printed an inch scale marked by tenths, and I put my own hash marks in between the tenths for my reference. The scale was taped to the Donny adapter so you can see it below the Picatinny clamp. Then, I took some video game tokens that I have had sitting on top of my desk forever, which happened to be exactly 1" in diameter and put them in a 1" scope ring.
20220609_103657.jpg


I simply started with the clamp up against my Donny Moderator, and moved it back while shooting groups. It took four sets of shots to zero it in, but the results were really impressive. Here they are:
TargetWithNotes.jpg


I don't believe that this will work on an Avenger unless you stiffen the barrel, but if there is anyone out there that wants to try, here is a link to a similar Picatinny clamp for your shroud for only $7. A quarter dollar is 0.95", so you could probably just use some tape around the stack of quarters to make it fit in a scope ring and not have to use tokens like I did.

Anyway, I would be interested in the feedback I get on this one.
 
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douger said:
im just confused if your gun is shooting great why mess with it, jut crazy to mess with that thing just not your device but the tuners in general
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It's a hobby. That's what we do. Why leave well-enough alone? Like adding a Top Rail Support from Saber Tactical.
I saw one guy had the "support" on a Impact Compact. Go figure.
 
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Blankshot17 said:
Love it. Question? Did you "degree" or "index" your barrel to have your pellets with the highest elevation? Just asking.
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Up until now, the Crosman's that I have modded all had the transfer port hole, so that would index the barrel by default. I have only have the Avenger barrel out once, and I seem to remember that there was a flat side or something that would index the barrel on that one, but I don't recall for sure :oops:

What did you mean "to have your pellets with the highest elevation"?
 
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SkeeterHawk said:
Up until now, the Crosman's that I have modded all had the transfer port hole, so that would index the barrel by default. I have only have the Avenger barrel out once, and I seem to remember that there was a flat side or something that would index the barrel on that one, but I don't recall for sure :oops:

What did you mean "to have your pellets with the highest elevation"?
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The indexing is from the video Air rifle pesting indexing fx impact barrel . So if you have a barrel liner that can be rotated then you end up with pellets that can be aligned at the highest point indexed to the harmonics of the system overall. Watch the video for details. So it all depends on if a Avenger barrel can be rotated similar to fx systems. If not then disreguard, I am just a tinker-er, but I love being a "sponge" when information is available for consumption.
 
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SkeeterHawk said:
Hello again, Shooting Enthusiasts!

I'm still trying to get my feet on the ground after returning from RMAC, and one thing that I wanted to do was to talk about the "ghetto" harmonic barrel tuner that I was using at the event. I got asked about it a number of times, so I thought I should just post it here.

In short, this is something that I threw together the week before RMAC as a quick test or proof of concept, and it made such a huge difference that I went ahead and left it on there for the competition.

View attachment 271462
This is the basic concept. It is just a clamping Picatinny rail clamped onto the Donny Adapter on my Avenger. I printed an inch scale marked by tenths, and I put my own hash marks in between the tenths for my reference. The scale was taped to the Donny adapter so you can see it below the Picatinny clamp. Then, I took some video game tokens that I have had sitting on top of my desk forever, which happened to be exactly 1" in diameter and put them in a 1" scope ring.View attachment 271463

I simply started with the clamp up against my Donny Moderator, and moved it back while shooting groups. It took four sets of shots to zero it in, but the results were really impressive. Here they are:
View attachment 271464

I don't believe that this will work on an Avenger unless you stiffen the barrel, but if there is anyone out there that wants to try, here is a link to a similar Picatinny clamp for your shroud for only $7. A quarter dollar is 0.95", so you could probably just use some tape around the stack of quarters to make it fit in a scope ring and not have to use tokens like I did.

Anyway, I would be interested in the feedback I get on this one.
Click to expand...
How do you stiffen a barrel on a Avenger bullpup?
 
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I haven't seen the Bullpup taken apart, but I am sure the concept is the same. Get rid of the cheap plasticy parts spacing the barrel from the shroud and replace it with solid carbon fiber. I had to shorten the aluminum shroud so that it all fit snug against the barrel and made it a concentric assembly along with the Donny Adapter. I really didn't like the barrel floating around in there...plus, then the harmonics are what they are and a small change in the regulator could change the nodes...and there is where the flyers come from? I don't think I have flyers anymore that aren't just a messed up pellet that I didn't catch.
 
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Fig said:
How do you stiffen a barrel on a Avenger bullpup?
Click to expand...
Again, I "won the lottery" on the carbon fiber that went over the barrel. The 11mm I.D. just happened to fit perfectly snug all the way down the barrel. I got lucky on that one, but have had to use JB Weld between the carbon and the barrel on other guns. It works awesome, but you can't take it back. At least JB Weld takes a while to set up...
 
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Blankshot17 said:
So it all depends on if a Avenger barrel can be rotated similar to fx systems. If not then disreguard, I am just a tinker-er, but I love being a "sponge" when information is available for consumption.
Click to expand...
That was a really interesting video. Thanks for sharing! I agree, I live for the data too.

I will look at the Avenger barrel the next time I have it apart and see if it can be rotated. Looking at the groups from rotating the FX barrel looks very much like that from the barrel tuner experiment. I wonder if that is ultimately what you are doing, just rotating the nodes around the gravity/effects of rifling/contour of the barrel itself. I imagine that you find out that most if not all barrels are not perfectly true when you get out to 100's of yards, and rotating them would give you another feather in your cap to help negate those unavoidable effects of manufacturing in a world with tolerances.

I have a 2240 mod on my bench right this second that I cut the barrel to eliminate the transfer port hole, so I can now rotate that one all I want. I may give this experiment a try on that gun, once I get it back together and shooting like I want.

Again, I agree that it is a blast to geek out on all of these technical details and how they work together.
 
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SkeeterHawk said:
Again, I "won the lottery" on the carbon fiber that went over the barrel. The 11mm I.D. just happened to fit perfectly snug all the way down the barrel. I got lucky on that one, but have had to use JB Weld between the carbon and the barrel on other guns. It works awesome, but you can't take it back. At least JB Weld takes a while to set up..
Click to expand...
SkeeterHawk said:
Again, I "won the lottery" on the carbon fiber that went over the barrel. The 11mm I.D. just happened to fit perfectly snug all the way down the barrel. I got lucky on that one, but have had to use JB Weld between the carbon and the barrel on other guns. It works awesome, but you can't take it back. At least JB Weld takes a while to set up...
Click to expand...
Gotcha. Thanks for the explanation
 
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