Video: Testing my FX harmonic dampener @102m with my Taipan Vet

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mtnGhost

mtnGhost

Member
Dec 15, 2018
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Defected from the PNW, United States
Did some additional testing of the little harmonic dampening system I made for my FX barrel kits. I have been on a mission to setup my longer FX barrels in such a way that I do not have to focus as much on harmonic tuning. I was also testing different barrel band configurations, but that turned out to be the easiest problem to solve for.

For this test, I tuned my Veteran with the 600mm FX slug liner - right in the center of the harmonic hell hole (960fps), Usually, with this tune - it shoots an inch more than it does from 950 or below or 995-1005), so I am already seeing much better results with this setup!

I pulled a few in this test, my trigger is setup in a two-stage configuration for hunting (and I don't care for the light factory configuration) plus I was shooting off my mat on a rocky surface with a chipped elbow 😂

Anyways, I'll share the details of the dampener once I do one last battery of tests with my 600mm and 700mm barrels. For now, I shot this with my iPhone after realizing my GoPro's SD card was at home 72 miles away 😭

https://m.youtube.com/watch?v=enOwQtvfHt0
 
Looks like whatever you are doing definitely has an affect on the group size. Looking forward to seeing the finished product.
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Indeed. The worst groups with this tune are around 2" when I'm not running any of the bushings around the liner in the shroud. Placement of the bushing assembly is another thing that I want to test further:

1591215150_12628144225ed8042ec36364.56797018.jpeg


The POI shift was expected, but I saw that shifted the worst when I just had some o-rings wrapped around my Taipan moderator and air cylinder, which I had installed to prevent barrel droop (and flex during shots):

1591214128_18588614815ed80030818e49.97915187.jpeg

Those do a good job when coupled with some form of a band that binds the two cylinders together, but without a band - I see POI shift randomly / severely between shots (the moderator winds up off to one side, usually the left side for some reason).

I'm happy with the results from this test, it showed me that it's possible to tame the harmonics and that I am on the right path. 960FPS has been a terrible velocity for this setup (but the ammo shot fine at that velocity in another rifle). My first zeroed group was at the bottom left of the target, when I had the barrel system setup as I thought would provide the greatest accuracy. I believe that I can dial it in further, and most importantly have a reproducible configuration!


 
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Someone smart should develop a BOSS SYSTEM turret at the end cap of the LDC OR MUZZLE WEIGHT to Be able to click (with detents) to fine tune the barrel harmonics. Then it permanently stays on THAT GUN don't mess with it. Matter of fact EPOXY IT ON PERMANENTLY. HARMONIC TUNING O-rings will eventually change due to age temp humidity what have you food for thought. Just thinking out loud. Yo!
 
Upvote 0
Someone smart should develop a BOSS SYSTEM turret at the end cap of the LDC OR MUZZLE WEIGHT to Be able to click (with detents) to fine tune the barrel harmonics. Then it permanently stays on THAT GUN don't mess with it. Matter of fact EPOXY IT ON PERMANENTLY. HARMONIC TUNING O-rings will eventually change due to age temp humidity what have you food for thought. Just thinking out loud. Yo!
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Great idea. I have been sketching out something along those lines using ER collets to grab the barrel, and then a threaded piece to adjust the barrel stretch. I came up with something that could work, without sacrificing the ability to thread a moderator, but I need to CNC one of the components (there's no way in hell that I could make it with the tools I have).

With that said, this dampener setup is simple and dramatically improves accuracy with otherwise inaccurate tuning.
 
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I think harmonic tuning for FINE tuning is an art form as much a science and especially with longer barrels shooting lower velocities this becomes more critical. I did some short experiments with different methods but in general I find that whatever you can do to dampen the overall sin curve vibration or close the extreme gap of high and low nodes, is helpful. I’ve been meaning to do more testing but I am liking the initial results of using heat shrink wrap on my barrel and barrel shroud. I build fishing rods and have used cork tape as well, wrapping the whole barrel with cork tape then shrink tuning it for serious dampening.
1591355105_10726108205eda26e1b57bf4.83221213.jpeg
1591355106_12874630435eda26e281f575.81243571.jpeg

 
Upvote 0
I think harmonic tuning for FINE tuning is an art form as much a science and especially with longer barrels shooting lower velocities this becomes more critical. I did some short experiments with different methods but in general I find that whatever you can do to dampen the overall sin curve vibration or close the extreme gap of high and low nodes, is helpful. I’ve been meaning to do more testing but I am liking the initial results of using heat shrink wrap on my barrel and barrel shroud. I build fishing rods and have used cork tape as well, wrapping the whole barrel with cork tape then shrink tuning it for serious dampening.
Click to expand...

Now that's creative thinking right there!!!

This press fit brass/acetal combo has shown a clear improvement, but I really want to test out a couple of other materials that could be the next level for dampening and absorption (I'm just trying to avoid having to build in anything permanent to the liner and shroud).

The other problem that I was encountering was barrel whip. This setup I'm using now seems to mitigate that a great deal with my 600mm barrel kit, but I haven't perfected it yet for the 700mm.
 
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