GTA
All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Topic started by: sshewins on May 15, 2011, 06:11:56 AM
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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.
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cool!
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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
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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
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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.
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This should tune your barrel - if you can still find one...
https://www.pyramydair.com/blog/2008/10/a-harmonic-tuning-muzzlebrake/ (https://www.pyramydair.com/blog/2008/10/a-harmonic-tuning-muzzlebrake/)
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This should tune your barrel - if you can still find one...
https://www.pyramydair.com/blog/2008/10/a-harmonic-tuning-muzzlebrake/ (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
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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.
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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
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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 (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
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That looks like a simple muzzle weight.... It might work, it might not, depending on how your barrel resonates....
Bob
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Hey guys, looking and drooling on the last issue of Airgun World...
Just wondering which issue that is?
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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
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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
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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. ;D
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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
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https:// www.impactguns.com/ (http://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.
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If the ID is 0.45".... how does it fit 1/2" - 7/8" barrels?.... Are you supposed to drill it out?....
Bob
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probly rubber
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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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yes they are made out of rubber. ;D fits tight on my barrel. have to stretch it on and hard to slide but effective. works.
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John, I believe it was march or may of 2011.
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Thanks sshewins.
Under the heading of “Sucker Born Every Minute,” here is how my newly arrived package reads:
begin blister pack insert
front
LIMBSAVER By SVL Sims Vibration Laboratory
Sharpshooter X-Ring
Sporter Barrel De-Resonator
Tightens Groups By Taming Barrel Vibration Waves!
When Performance Counts 12051
Go To LimbSaver.Com for additional installation instructions and warranty information.
back
Sharpshooter X-Ring (SM) Fits ˝” to 7/8” Barrel Diameter
The Sharpshooter is a unique barrel accessory manufactured from NAVCOM* that tunes the 5 main ballistic vibration waves that affect shot grouping. These waves include: expansion, torsion, standing, whip, and elongation. Each of these individual waves negatively affects the barrel and the Sharpshooter is specifically designed to control them. By reducing this energy and tuning the dampening characteristics to a specific location on the barrel, you can consistently control muzzle movement during lock-up time which translates to greater accuracy.
Installation Instructions:
To install the Sharpshooter, simply apply a thin coat of gun oil to the inside of the part. Slide the product over the end of the barrel. The Iron Sight may need to be temporarily removed for the installation. To tune the Sharpshooter for peak performance, shoot groups with the product located 3/4” away from the stock on a rifle with a non-floating barrel, and 3/4” from the end of the muzzle on a floating barrel. Adjust the Sharpshooter up or down the barrel in 1/2” increments to fine-tune. You may need to squirt some gun oil underneath the part to move it.
Sims Vibration Laboratory (360)427-6031 1-877-257-2761 03/11 rfid: 6 97438 12051 8
end blister pack insert
I’m thinking one could snug this up on a too-small barrel with judicious use of tie wrap(s).
Next time I remove my shroud, will play with it. Shouldn't cost me more than a few thousand rounds and my benched artillary hold needs work anyway.
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John, I believe it was march or may of 2011.
Found it. Page 74 April '11 issue. KILLER article. Really makes clear what's happening.
Firing causes muzzle to start wagging back & forth, up & down, or some combination of both. The vibration damps out but not until after the pellet has exited.
Muzzle swings out, slows to stop, reverses direction, accelerates back toward and thru neutral (where it started upon sear release) or near neutral, and out in the other direction. Or it may carve out a cloverleaf-like path. Who knows? Who cares? Nobody! Because the exact muzzle path is irrelevant. What’s relevant is that the path is periodic. Like a pendulum.
Meanwhile(milliseconds), pellet is accelerating down the bore.
Like the pendulum, muzzle is moving fastest as it passes thru or near neutral. You prefer pellets (e.g. Brand B) NOT exit in that near-neutral fast-moving muzzle region; they will tend to have more widely scattered points of impact. No, you are looking for Brand A pellets which just happen to exit while the muzzle is in the nether slow-moving region of its extreme excursion; those pellets will tend to be more tightly grouped. Yeah, that tight group may be out in the cow pasture but that can be fixed by tweaking sights or reticles.
Oh, but you like Brand B for some reason (ok, like they maybe don’t cost an arm or leg?…or…whatever). Then tune your barrel…yeah, modulate your barrel frequency, bro.
Whadya thimk? you buy any of that for a dollar?
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I'd go a $1.225. delivered ;D sounded good to me.
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So John is saying: you can tune your barrel with either 1. pellet choice or 2. some device like Limbsaver. Am I right?
By the way, thanks sshewins for bringing this up. Its fascinating,, never heard of such a concept. It'll be fun to play with this when the weather changes to cooler.
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First, my apologies if you all have seen this post in other gates, but I thought it worth repeating here as well.
If you have a Crosman Titan or a Benji Titan (or you might be able to replace the shroud of a Trail with a brake from a Titan), you might not need one of them. I shot three groups of 10 pellets each at 20 yds from a bench with a CP 4-16X40AO scope set at 10X. The pellets were 14.3 gn CHPH and Crosman Pointed. The first two groups are with the brake bottomed out on the muzzle. Physically, there is no way for the pellet to strike the brake after exiting the muzzle unless the crown is really messed up.
I loosened the two set screws just enough to move the brake. I set it to where the two set screws are about 1/2 inch from the muzzle of the rifle. You can clearly see the difference it made in the third photo. I shot five CPHP and five pointed with the same parameters as above.
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group is tighter...dang...English House Sparrows just hate that. ;D
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Thanks Deane,,,I hadn't seen it on other gates,,,,wow,,,,thats amazing. Thanks