Author Topic: Barrel harmonics (Read 7666 times))

sshewins · « **on:** May 15, 2011, 06:11:56 AM »

Hey guys, looking and drooling on the last issue of Airgun World, I couldn't help but think how much this article could be of benefit to us. Naturally, they didn't get to the good stuff this month, thats next months topic.

In a nut shell, they were going to go over how to determine how to add the nessesary weight and where (not much and near the muzzle) to slow down the negative effects of harmonics in the barrel. They showed a 7 shot group w/o added weight and a group with. It went from around 3/4" IIRC to under 1/2". I dont remember how far away the target was. Just thought you guys might find this interesting in our quest for accuracy. I'll report back after next issue shows up.

Mark 611 · « **Reply #1 on:** May 15, 2011, 01:07:11 PM »

cool!

lloyd-ss · « **Reply #2 on:** May 16, 2011, 12:37:43 AM »

I wonder if it's still a trial and error method, or if they have some guidelines to help get started with an approximate weight and location?
Should be interesting.
Lloyd

rsterne · « **Reply #3 on:** May 16, 2011, 01:11:57 AM »

I have tried a series of barrel weights on the end of the skinny 7/16" Crosman barrels.... I made a series that varied by only about 5 grams over a range from zero to about 1.25 oz (35 g.).... Believe it or not, I was able to see the group size shrink and then expand again as I worked through the 7 different weights....

Unfortunately, changing ANYTHING else made the optimum weight change as well.... A different pellet or velocity (the gun had an RVA) meant that the "best" weight changed as the pellet would leave the muzzle at a different point in the barrel vibration....

My conclusion was that once you find an optimum combination of pellet and velocity for your barrel.... you MAY be able to improve the group size by experimenting with a different weight on the end of the barrel.... and that VERY small changes are necessary on flexible barrels....

Bob

airiscool · « **Reply #4 on:** May 16, 2011, 01:21:17 PM »

No reason it shouldn't work, it's an old idea brought new once again.

Years back Browning had a threaded fitting on the end of some of their powder burner rifles. It had numbered settings.

The idea was to experiment with different types of ammo that were going to be used in that rifle, by turn the threaded fitting in, or out, and firing groups until you got the maximum dampening, therefore the tightest groups, for that brand/weight of bullet. Then write down the setting for that bullet.

There after, any change of ammo and you just turned the fitting to the setting that your previous testing showed was best for that bullet.

A great idea that didn't realy catch on. My guess as to why,.... based on my experiance was that very few hunters wanted to spend the time and ammo money to get the best from that barrel. The few that want to get the best possable accuracy that a gun may be capable of usually hand load for a certain rifle/bullet combo, which can get even better results.

Makes me wonder if an adjustable length muzzle break would work on AG's ?

Paul.

K_sqrd · « **Reply #5 on:** May 16, 2011, 02:04:39 PM »

This should tune your barrel - if you can still find one...

https://www.pyramydair.com/blog/2008/10/a-harmonic-tuning-muzzlebrake/

lloyd-ss · « **Reply #6 on:** May 16, 2011, 05:53:18 PM »

Quote from: K_sqrd on May 16, 2011, 02:04:39 PM

This should tune your barrel - if you can still find one...

https://www.pyramydair.com/blog/2008/10/a-harmonic-tuning-muzzlebrake/

Wow, quite a coincidence. Shows how few REALLY new ideas there are and how bad my memory is. The Lloyd in the blog comments you referenced is me! Does look like a good idea, but a lot of work to put into practice.
Lloyd

jps42 · « **Reply #7 on:** June 05, 2011, 12:12:28 AM »

The way i tuned the barrel is by using a #32 rubber band. I made the rubber band into a tight ring which fit around the barrel. I then slowly adjusted the rubber band position till i got the best group. When i finished tuning it i shot a .75 inch group at 30 yards with CPHP.

ncpackrat · « **Reply #8 on:** July 03, 2011, 10:41:26 PM »

Ok as I remember the reason the brake didn't go over good is this.and we took some off and built a new one.Yes it did work for the harmonics BUTit also had a big down fall as to loosening all the screws in the guns.Scopes especally!So several of us here had to replace them and the screw problems went away.Ernie

Nathan · « **Reply #9 on:** July 03, 2011, 11:15:54 PM »

What about trying one of these

http://www.cabelas.com/product/Sims-LimbSaver174-Barrel-De-Resonator/741294.uts?Ntk=AllProducts&searchPath=%2Fcatalog%2Fsearch.cmd%3Fform_state%3DsearchForm%26N%3D0%26fsch%3Dtrue%26Ntk%3DAllProducts%26Ntt%3Dlimbsaver%26WTz_l%3DHeader%253BSearch-All%2BProducts&Ntt=limbsaver&WTz_l=Header%3BSearch-All+Products

Nathan

rsterne · « **Reply #10 on:** July 03, 2011, 11:23:09 PM »

That looks like a simple muzzle weight.... It might work, it might not, depending on how your barrel resonates....

Bob

john · « **Reply #11 on:** July 04, 2011, 10:59:03 AM »

Quote from: sshewins on May 15, 2011, 06:11:56 AM

Hey guys, looking and drooling on the last issue of Airgun World...

Just wondering which issue that is?

dkwflight · « **Reply #12 on:** July 04, 2011, 02:45:17 PM »

Hi

The limb saver has to stay in place on the barrel, so check the interior diameter.
The idea being to slide it back and forth on the barrel until you get the smallest groups.
If it moves easily then you might move it during cocking or hunting and loose any sweet spot you might have found.

Part of what you are doing by trying different weight pellets is tuning for a harmonic dead spot because heavier pellets move slower than light pellets.
Dennis

rsterne · « **Reply #13 on:** July 04, 2011, 03:55:48 PM »

Ahhhhhhh.... If the limb saver slides back and forth on the barrel I missed that.... I assumed because the end you can't see is quite a bit larger OD it just fastened to the end of the barrel....

Bob

aack73 · « **Reply #14 on:** July 04, 2011, 04:30:53 PM »

i have a limb saver for my 17hmr. it's very tight. does not move around.it's so tight it was difficult to get on and adjust. the key would be for it to fit the barrel tightly so it stays put. probably be a little to big for airgun.?? they make them for a bull barrel and a standard barrel.

Pete · « **Reply #15 on:** July 04, 2011, 04:48:08 PM »

One off the best one I have seen was a shrould
that could be twisted to put tention on the barrel.
It was threaded into the brake..by twisting it you
put pressure between the breech block & brake

john · « **Reply #16 on:** July 04, 2011, 06:58:34 PM »

https:// www.impactguns.com/ limbsaver-standard-barrel-de-resonator-12051-697438120518.aspx

The New LimbSaver® Barrel De-Resonator is designed to dampen out unwanted vibration by shortening the overall settling time of the barrel. The accuracy benefit is immediate, providing sub-minute angle groups with over-the-counter factory ammunition. This easy-to-install unit simply slips over most standard barrels. Designed and manufactured with our proprietary NAVCOM™ (Noise and Vibration Control Material), and engineered for optimum performance utilizing Sims Vibration Laboratory’s DTMS (Decay Time Modification System). If you are looking for performance & accuracy, trust LimbSaver®, the makers of “Products That Work!”™ *Note: Barrel De-Resonator can be used on a muzzleloader without a ram rod.

Technical Specifications

Weight 29.70g
Length 1.62"
Diameter 1.44"
Information .45" inner diameter (for 1/2-7/8" sporter barrels)
Part # 12051

They don't mention the bull barrel version.

rsterne · « **Reply #17 on:** July 04, 2011, 07:15:27 PM »

If the ID is 0.45".... how does it fit 1/2" - 7/8" barrels?.... Are you supposed to drill it out?....

Bob

john · « **Reply #18 on:** July 04, 2011, 07:17:46 PM »

probly rubber

MichaelM · « **Reply #19 on:** July 04, 2011, 07:23:37 PM »

Quote from: airiscool on May 16, 2011, 01:21:17 PM

No reason it shouldn't work, it's an old idea brought new once again.

Years back Browning had a threaded fitting on the end of some of their powder burner rifles. It had numbered settings.

The idea was to experiment with different types of ammo that were going to be used in that rifle, by turn the threaded fitting in, or out, and firing groups until you got the maximum dampening, therefore the tightest groups, for that brand/weight of bullet. Then write down the setting for that bullet.

There after, any change of ammo and you just turned the fitting to the setting that your previous testing showed was best for that bullet.

A great idea that didn't realy catch on. My guess as to why,.... based on my experiance was that very few hunters wanted to spend the time and ammo money to get the best from that barrel. The few that want to get the best possable accuracy that a gun may be capable of usually hand load for a certain rifle/bullet combo, which can get even better results.

Makes me wonder if an adjustable length muzzle break would work on AG's ?

Paul.

They Call it the BOSS system.... they still make it and its a VERY effective system even with the best handloads you will still be able to tune the barrel to get even better results..

remember no one load is good for everything so this lets you take one rifle and find the optimum settings for the 2 or 3 or whatever different loads you may be using for different hunting/shooting situations...

NOW is it a pain in the butt and take alot of work to get setup.... you betcha!!! LOL but if your wanting the best your gun can produce with different loadings then this is probably the best system out there for it

Dont have one wish I did though LOL and I HAVE thought about coming up with a similiar idea for AG's.... nother one of those projects that may get finished one day LOL

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Barrel harmonics

Author Topic: Barrel harmonics (Read 7666 times))

airiscool

dkwflight