Barrel harmonics

[aack73]

yes they are made out of rubber. fits tight on my barrel. have to stretch it on and hard to slide but effective. works.

[sshewins]

John, I believe it was march or may of 2011.

[john]

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 ½” 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.

[john]

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?

[aack73]

I'd go a  $1.225. delivered sounded good to me.

[neric]

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. 

[Deane]

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.

[john]

group is tighter...dang...English House Sparrows just hate that.

[neric]

Thanks Deane,,,I hadn't seen it on other gates,,,,wow,,,,thats amazing.  Thanks