Rifle Barrel De-Resonator


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BIGJACK
July 4, 2006, 08:29 AM
Has anyone tried the Sims barrel de-resonators, or others, and do they have any noticeagle effect?:confused:

I have an el-cheepo Rossi single shot .243 that shoots resonably well after Rossi did some manufacturer "adjustments". However, the variation in point of impact and grouping with different loads is amazing. :eek:

I shot two different loads, from the window of my pickup(resonabley stable) yesterday 100gr BTSP, one with 44gr 4350 and one with 41.3 gr of W760. The 4350 was right on with about a 1.5"moa :) while the W760 was on but with a moa of about 4".:mad:

My question is, will the de-resonator help these variations??:uhoh:

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Smith357
July 4, 2006, 09:59 AM
This is normal that is why you hunt with the loads you sight the rifle with.

I have seen these de-resonaters and they do work to a certain extent, it will not bring differnt load to the same point of impact but it may make you groups a bit smaller. I had a Browning BAR MKII .30-06 that came with the BOSS system it started as a 3 moa shooter out of the box. It took a bit of tuning but once I got the load and the setting matched up it was a sub MOA rifle.

rbernie
July 4, 2006, 10:27 AM
http://www.thehighroad.org/showthread.php?t=207650

rangerruck
July 4, 2006, 12:48 PM
not really, the rossi , nef and other single shot/falling blocks are about as stiff as you can get. if you are getting 1.5 groups with 1 ammo, that is a good starting point, it just doesn't like the other ammo. try to tighten up that group with making sure you rchamber/bore is superclean, and then put it out, covered ,in the heat for a couple of days . Such as in your water heater room, or your garage, with a synthetic lube in the bore, with the open ends plugged up with earplugs, wax, something. molyfusion is the best, but you may just try rem-oil first , and see what happens.

BIGJACK
July 4, 2006, 03:53 PM
Me Again. Just a comback of sorts. I have a SS Stalker Browning 30-06 that I have shot moa groups on the same day with several different loads all in, for all practical sense, the same spot. I feel confident with it regardless of which brand or load I put in it. I have a Remington 700 in .222 that is not quite so tollerant of loads but varies not more than a couple of inches with about anything i put in it. IS this unusual?

I have couple of 22s one, an old Remington, and the REm will not stay on a sheet of note book paper with anything other than CCI mini mags and it will hold them into about 1 inch at 50 yds.

Based on what I have heard and going back to the other thread I think I will just spend that 12-14 bucks on components and forget about the de-resonator.:D

jeepmor
July 4, 2006, 04:35 PM
the concept is that a barrel goes through a harmonic cycle when fired. The boss on teh end of the barrel is effectively a weight that can be moved along the axis of the bore. the natural frequency of the system is now tuneable by moving the weight on the end of the barrel.

The idea is to make the barrel be in the same relative harmonic position with each shot. this harmonic is determined by the weight of the bullet and nothing more. not the powder charge, not the brand of ammo, but simply the mass of the bullet itself.

so, for the guy that got consistent poi out of his browning, it is likely that the same weight bullets may have been used, even though the brand varied. Tuning one of these bosses can be a lengthy process with several hundred rounds spent to get the best results.

do a search on it, many people have done this shooting intensive exercise and pretty much tried about every setting there is. It may/will vary with each firearm due to minor manufacturing differences. A few 1/10,000ths of an inch in milling will make a difference in the natural frequency of the barrel. However, there are so many folks out there that have done this research that you could probably find a good starting point for a setting.

what you are doing is making it so that as this barrel naturally vibrates when fired, the barrel will have natural sine curve that it goes through, tuning puts it in the same position in this curve when the bullet exits the barrel, improving grouping.

jeepmor

BIGJACK
July 5, 2006, 09:21 AM
by Jeepmore this harmonic is determined by the weight of the bullet and nothing more. not the powder charge, not the brand of ammo, but simply the mass of the bullet itself.

Are you sure about this. I am an Engineer, old one but never the less i still understand harmonics, resonace and such and I would think that the energy of the projectile, which relates directly to the charge, would enter into the equation, along with the weight of the projectile. In other words I would think, with out knowing any better, that a bullet traveling down the barrel at 3500fps would generate a hormonic which was different then it would be with the same bullet traveling at 2500fps???????

by the way, with the browing, the bullets were of different weights, 150, 165 and 180 gr. poi for all relatively the same.

JohnBT
July 5, 2006, 09:27 AM
Varmint Al has a good read on it at http://rifle-accuracy.com/harmonics.htm

"From the moment that trigger is pressed and the firing pin strikes the primer until the bullet leaves the muzzle, a series of many vibrational impulses begin in the rifle, all of which are transmitted to the barrel in various magnitudes. These include such minor things as; the trigger sear releasing the firing pin, the firing pin moving forward, striking the primer, and the cartridge being moved forward. The powder then begins to ignite, and the bullet starts moving forward and engages the rifling. Because of the twist of the rifling, the bullet while it is being propelled forward, begins to spin imparting a small but measurable torque, but more importantly as it traverses the barrel it also sets up a circular vibrational pattern, or arc. The heat of the burning powder along with the pressure wave generated by the expanding gasses start another vibrational pattern that is induced into the barrel. All of these movements cause the barrel to stress and vibrate with a number of different harmonic patterns which if not controlled by some means..."

BIGJACK
July 5, 2006, 04:36 PM
Thanks john, thats more along with my thinking, right or wrong, Thanks

BIGJACK
July 5, 2006, 04:46 PM
john, I went back and read the report that you reccommended and that is a very informative piece of work. It sheds a lot of light onto tuning a rifle and I am sure would help anyone in that effort.
Again, Thanks

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