Jump to content
308AR.com Community
  • Visit Aero Precision
  • Visit Brownells
  • Visit EuroOptic
  • Visit Site
  • Visit Beachin Tactical
  • Visit Rainier Arms
  • Visit Ballistic Advantage
  • Visit Palmetto State Armory
  • Visit Cabelas
  • Visit Sportsmans Guide

Barrel Dampener for harmonics


Gibbs

Recommended Posts

I love to hear opinions and thoughts.  I have read and heard about ways to dampen or change the barrel harmonics of rifles.  What I understand is that there is a sound wave that travels at the speed of sound through metal when the cartridge is fired.  VERY fast, much much faster than through air.  In fact it is said that this shock wave hits the end of the barrel, heads back to the breech, then back again to the end of the barrel several times before the bullet has had a chance to exit the muzzle end.  I have read that it is important that the shock wave or "harmonics" have not coincided with the exit of the bullet at the muzzle end.  I've even Seen a system on one rifle, in video, BOSS (Browning's paten on Ballistic Optimizing Shooting System )  *google search BOSS barrel tuner, and you will see this.  You tube video even has a clip on it.

 

What's the opinion of the .308 crowd?  There is only a short distance between the gas block and the end of the barrel and was not sure that harmonic dampening can have a benefit in that short distance.

 

Link to comment
Share on other sites

  • Replies 70
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

When I was a kid Brownell's sold these rubber ball looking things that you slid onto the barrel and then adjusted the location to "tune" the harmonics. I was pretty sure it was a gimmick but after researching the ladder system for tuning reloads for a rifle I might be swayed. The barrel moves up and down during the vibration, the idea is to get the bullet to exit the muzzle at the top or bottom of the wave where it sits still the longest. Here is some reading on it;

 

 

https://www.google.com/webhp?sourceid=chrome-instant&rlz=1C1SFXN_enUS501US504&ion=1&espv=2&ie=UTF-8#q=reloading%20ladder%20method

Link to comment
Share on other sites

When I was a kid Brownell's sold these rubber ball looking things that you slid onto the barrel and then adjusted the location to "tune" the harmonics. I was pretty sure it was a gimmick but after researching the ladder system for tuning reloads for a rifle I might be swayed. The barrel moves up and down during the vibration, the idea is to get the bullet to exit the muzzle at the top or bottom of the wave where it sits still the longest. Here is some reading on it;

https://www.google.com/webhp?sourceid=chrome-instant&rlz=1C1SFXN_enUS501US504&ion=1&espv=2&ie=UTF-8#q=reloading%20ladder%20method

I was somewhere in the past month that had theses and I thought WTF IS THAT?!?!

Question answered

Edited by shepp
Link to comment
Share on other sites

Tuning barrel harmonics with balls and clamp-on weights has been around for a long time.  If you're not making money shooting in competitions, then you're chasing ghosts. 

 

You CAN dial it in, but for what purpose?  Military snipers aren't out there adjusting a ball on their barrel, and that's "defending lives."

 

Where's Owl right now, to give the Sniper Feedback?

Link to comment
Share on other sites

Interesting in my search I found a thread in a "Machinist Forum" site that even they are aware of barrel harmonics and nodes  and were discussing "ringing a barrel" to determine where to cut the barrel.  http://www.practicalmachinist.com/vb/gunsmithing/ringing-barrel-127452/

 

I was thinking that one could "tune" a barrel for various handloads that using it might tame the barrel harmonics and vibration a bit.  As 98Z5V had pointed out, military snipers use weapons that are not "accurized" with tuners, per se, but I am betting that they do a lot of work with handloads to figures out what works the best in what barrel/rifle.  For hand loaders, we are aware of barrel harmonics and what a good load will do for accuracy or lack thereof.  Trick is to get the bullet out the barrel at the right time when the barrel has the least amount of any whip/movement at the crown, or at least make sure the load leave the muzzle when the barrel is in the same position of movement shot after shot. 

 

I do have a small aluminum clamp in my box of stuff that I think came from a 22 scope or laser set up that has 2 allen head bolts and fits around the .308 barrel.  I have a 100 yard range in my back yard (live in the country) which is open 24/7 and I made up some rounds of the same bullet, powder, primer, brass, etc and can take a look at with and without and see if there is some benefit.  The ONLY benefit, would be if you could dial the barrel into your bullet weight and small variances in powder charge, seating depth, would be negated.  If that can't happen, then it's just another variable that has to be set "right" for it to work as it should.

 

I'll try out some targets and loads,even though this is not a BOSS type of system, it might give the barrel some dampening of sorts in an experiment. 

 

Other thought is the actual flash hider on the the end of my barrel.  Would it shoot differently without it?  I would think it might since it adds weight, and torque on the threads at near the barrel crown.  Now I wonder what would happen if the flash suppressor were further out on the barrel by using 2 or 3 crush washers (to keep alignment correct for the non slot end being at the bottom)? 

Link to comment
Share on other sites

I did stumble across a link kind of on the same thought as above about the movement of the flash suppressor, of a bench rest rifle using a tuner on the end of the barrel.  Seems like a lot of scientifc analysis and somewhat interesting views in 3D of how barrels move during firing, according to frequencies.  link ->  http://www.varmintal.com/aeste.htm  

Link to comment
Share on other sites

If such a device really had a great added value, and did what people say it does, then you'd find the product in David Tubb's online store.  It's not there.

 

Likewise, he would have it on the Tubb 2000 rifle. 

 

That kinda answers it for ya, right there.

Link to comment
Share on other sites

I just put my comment in there after searching what he offered for a barrel donut.  No kidding, if it really changed round impact in a dramatic way, he'd offer it for sale and use it on his flagship target rifle. 

Link to comment
Share on other sites

Well, he does have a tune-able muzzle brake for the 2000.  http://www.davidtubb.com/catalog/view/theme/davidtubb/pdf/product_information/T2K_brake_sheet.pdf

It states it has an optional lock nut to tune vibrational nodes. 

Cost is $119.00 and product description is here: http://www.davidtubb.com/muzzlebrake?search=Brake&description=true  Thead is not for a AR .308 though, it is 3/4 - 28 pitch thread.

 

(You'd think I'd learn to spell check before posting)  LOL

 

No, I don't think donuts are the answer, nor are rubber rings. What Browning patented and what that one guy has at his site is more on the idea of muzzle devices that are fine threaded for minute changes in the very end of the barrel, even on David Tubb's "Tubb 2000 Custom Muzzle Brake".  If you had a 5/8 -24 locknut (thin) one could do something similar with the flash suppressor on the end of the AR 308 rifles. 

 

This you tube video of David Tubb talks about tuning your  rifle to find a sweet spot with this brake and advancing it out or in a bit for that sweet spot.  https://www.youtube.com/watch?v=dqvVHS6T_sM

 

 

If one were well versed in engineering and metallurgy, you might create harmonics in a rifle barrel and say "Cut this one to 16" + 0.225" and hit the magic spot of node vibration for that particular barrel.  But, they are mass produced things (barrels) and as such they are generally cut at 16 1/4" just to make sure it is past the 16" minimum and then the barrel will find it's niche with certain bullets/powder/primer/cases  and handloaded to where the  ammo is in tune to the barrel rather than the barrel in tune to the ammo.

Edited by Gibbs
Link to comment
Share on other sites

My  bullet is going so fast it cant remember where it came from when it hits steel at 500....although the groups could  be tighter  hmmmmm.....what to do?    :)   Wash

 

subject for harmonics test:   6.8spc2.....5R .....16" full twist fluted one of a kind barrel...well maybe three of a kind........

 

 

IMG_1243_zps0de4f2ca.jpg

Edited by washguy
Link to comment
Share on other sites

Gibbs, you've shown that you can shoot well enough to test something like this out.  Have at it.  Pick up something to tune a barrel, test that thing out, makes your groups, and let us know how it does or doesn't. 

 

For you, with the way you shoot, that's easy. 

Link to comment
Share on other sites

My  bullet is going so fast it cant remember where it came from when it hits steel at 500....although the groups could  be tighter  hmmmmm.....what to do?    :)   Wash

 

subject for harmonics test:   6.8spc2.....5R .....16" full twist fluted one of a kind barrel...well maybe three of a kind........

 

 

IMG_1243_zps0de4f2ca.jpg

 

Dude!  Is that the limited edition Aloha Snackbar Chancla?!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...