Need Help With a Tuner

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BlackwellADB said:
I also have enjoyed this thread. I have been using a tuner for over 10 years on 6PPC and was told it was a waist of time & effort by most of the top shooters who are somehow using them today, Hmmmmmmmmmmmm.

As I said 10 years in & if you want to find out the the real concept of them talk to the man who wrote the post before this one. I have used it pretty much exclusively and it really works and employs the KISS theory.

Thanks to Gene for pioneering the idea.

Al
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Al, glad to hear you are pleased with and have had good results with your tuner.

Thanks for the kind words but I must say I have not pioneered anything on my own. Oh,, I've simplified and improved here and there but most of what I know and share has come from bits and pieces of what others have done during the past many years.

Jackie Schmidt is one that must be congratulated for his pioneering work and perseverance with tuners.

Thank you Jackie! :D We owe you a lot.

Sincerely

Gene Beggs
 
Gene Beggs said:
Al, glad to hear you are pleased with and have had good results with your tuner.

Thanks for the kind words but I must say I have not pioneered anything on my own. Oh,, I've simplified and improved here and there but most of what I know and share has come from bits and pieces of what others have done during the past many years.

Jackie Schmidt is one that must be congratulated for his pioneering work and perseverance with tuners.

Thank you Jackie! :D We owe you a lot.

Sincerely

Gene Beggs
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You are welcome, Gene.
 
Giving credit where credit is due.

I know Jackie was an early promoter and inventor of the tuner, anyone who can build a winning rail gun out of old boat parts has to be taken seriously, LOL. I am greatful to him and all those who got the tuner developed and approved in the early days. Gene introduced it to me at a Super Shoot about 10 years ago and I have used one on every barrel since. He spent a lot of time with me explaining the concept, sine curve, adjusting and what to expect from it and also what not to expect. I truly learned alot. I tried some other designs but always ended up back to the ones I bought from Gene or copies that I made out of other metals I tried. Jackie, you'll laugh that I now use a piece of SS from a bent boat prop shaft to make them, in FL you can get them all over & real cheap. For those of you playing with the concept, as said before, don't over think a fairly easy thing to do and don't think it will fix a bad barrel or wrong load formula, IT WON"T. It, as the name says, tunes the gun. As they say on TV, "try it you'll like it".
 
Wilbur said:
I don't know who ended up with any of Doc's stuff....maybe Dorsey, his brother. That rail was awesome!

Bob Meadows it was - looked it up.

http://www.legacy.com/obituaries/atlanta/obituary.aspx?pid=99841131
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Till I read that obit I had always thought Carolyn was his daughter. For those interested Carolyn Dogen is and has been a member of the NRA Board of Direstors for many years.

Doc always called himself a "chicken doctor"! He did love rimfire competition for sure.



.
 
I
t is all aluminum and it changes its length according to ambient temperature. The tough part was figuring out the total weight and distribution to get it to maintain the tune over as wide of range of weather change as possible.
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Jerry

Is it the length of the tuner that's more important than the weight? Or does the increase in length create the same effect as an increase in weight would?
 
Tony C said:
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Jerry

Is it the length of the tuner that's more important than the weight? Or does the increase in length create the same effect as an increase in weight would?
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Most shooters now are using tuners in about the 3-5 oz range. I tried them and had to readjust them from time to time. Fudd Hamilton made me a couple of 10 oz tuners. With them I could tune a barrel and it would stay in tune. Trouble here was I had to turn some off the barrel to make LV with LCS scopes.

With a tuner hanging over the muzzle the POI will change some during adjustments.

Anything you hang on the barrel will change the performance some.

Several years ago George Kelbly and Paul Gottshal (sp?) clamped a 5# weight to a barrel. He said it lowered the POI a bunch! He still has that thing if you want to borrow it.

.
 
Jerry H

How does the length (which changes due to temperature) of the tuner keep the rifle in tune? How does this work? What is being effected? I don't have a strong physics background. Very interesting!

A "set it and forget it" CF tuner would be incredibly awesome.
 
This is for a RF and it's bullet exit timing. A RF has about 2.1 ms barrel time vs a CF of about 1.25 ms. I have no idea how it would function on a CF. Your tuner is set on one of two places in theory. The high or the low position of the barrel when it is at the minimum motion. When you have to change the tuner setting, it's only a little bit. By using the expansion rate of aluminum with the appropriate weight distribution of my tuner, it self adjusts the center of mass position of the tuner in relation to the barrel end to maintain the grouping at the same "number setting" despite different ambient temperatures. Keep in mind that a RF doesn't heat the barrel up very much. I actually use some AC pipe insulation to keep the heat in.
 
If the muzzle is not moving, such as at the top or bottom of muzzle motion, there is no compensation. This means that top and bottom are bad places for the bullet to exit. Not the worst, but bad. Compensation refers to a situation in which slower bullets, which exit the barrel later, are launched at a higher angle, thereby hitting the target at the same elevation as faster bullets. For this to happen, the muzzle angle must be rising when bullets exit. In fact, one can calculate the rate of rise necessary to perfectly compensate for a range of exit times within a group. The worst motion is a dropping muzzle angle, which causes the slower bullets to be launched at a lower angle, hitting the target even lower than if the muzzle were fixed.
 
I agree but, I believe there is a place just before the the apex or after the valley that provides positive compensation. This tuner prints identically with Lapua and Eley even though they average 30 fps different plus the ES within each, PC is occurring.
 
Many years ago, Merrill Martin thinned out the middle of a heavy barrel on a match .22, added some heavy split collars to the muzzle, and was able to tune out the vertical difference between standard and high velocity ammunition at 50 yards (If memory serves). An account of his experiment was published in Precision Shooting. I believe that this was the first account that I read about someone modifying a rifle to accomplish positive compensation. This was before I had read of tuners being used on rimfire bench rifles. Many years later, when Varmint Al was publishing the results of his computer simulations of barrel motion and various modifications' effect on vertical dispersion, I suggested that he run a simulation for a barrel that was thinned in its middle. He did, and if you look hard enough on his site, you may be able to find it. It worked. For a CF rifle caliber, it caused the bullets to exit the muzzle on the LH side of the muzzle rise curve, similar to what a longer barrel or muzzle weight did. Some time before that, while I was writing equipment articles for Shooters News, I arranged to have Lynwood Harrell (who was making RF tuners that Ron Hoehn was selling) and Lou Murdica work together to do a test of his tuner on a 6PPC. After that Lou used one on his HV at the nationals. I asked him if it shot better with the tuner. He said that it did.
 
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You can use an external ballistics calculator to find the increase in muzzle angle required to get the 30 fps slower lot to hit the target at the same elevation. Divide the increase in muzzle angle by the increase in bullet exit time, and you have the rate of muzzle angle change (muzzle angular velocity) that your tuner must be creating. Where in the muzzle motion wave this is occurring is not as important as that it does occur. In my experience, which is almost entirely with centerfire, it is hard to get enough compensation. Overcompensation rarely occurs. So for the typical rifle, the best point in the wave is where it is moving fastest, which is halfway between the valley and the peak. If that point creates overcompensation, then you can move away from it in either direction to reduce muzzle angular velocity to the perfect value.
 
One thing that has not been mentioned much is that by adding weight to the muzzle it is possible to move a node to a slightly lower velocity and pressure. Some years back I did an experiment that confirmed this. I tuned up with a particular barrel, bullet, powder combination to excellent accuracy, but the load required more effort to get the powder in the case than I liked. By adding some weight to the muzzle I was able to achieve the same tune with slightly less powder, and when I removed the weight, it went back to where it had been. The weight was a Possum Hollow case trimmer. It was secured flush with the muzzle on the underside of the barrel with a double wrap of tightly stretched electrical tape, which also proves that one does not have to own a lathe and a mill to do a little experimenting ;-)
 
Perhaps, I know this going to be laughed at, a skinnier barrel might be in order. A tuner can do it's job easier with a more flexible barrel. Gene Beggs once made me a tuner for an 1.450 unlimited CF and it weighed a LOT, but still didn't do anything as far as helping the state of tune.
 
Back in the day there was an article in Precision Shooting about Bill Calfee that featured one of his XP 100 pistol , CF to RF conversions. It had the original plastic stock with an added custom bipod, and a small tuner. The barrel contour was a relatively slim cylinder, except for a few inches in the middle that had been turned to a smaller diameter. It occurred to me that this was probably to allow the tuner to be lighter, which would help the balance of the bench pistol. Some time later in one of these forms there was a tuner related thread that included posts by Calfee. In it I recounted the story about the PS article and referred to my surmise of why he had slimmed the barrel in its center. I called it a hinge point. Calfee replied that he liked the term and asked my permission to use it in future writings. Of course I said that that would be fine by me.

Some time back I saw Lou Murdica use a scaled up Stewart tuner (double ring, similar to the Beggs) on his rail gun. The barrel was a typical large cylinder, and he was able to tune it using the tuner, which was considerably larger than the standard version.
 
Richard said:
Jerry, your not going to laughed at by me. The longer, more flexible bbl is easier to tune. It will also shoot more vertical out of tune.

Richard Brensing
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Agreed...100%!! Simply speaking, it could be said that...that's what tuners do!

In a previous post I mentioned that I'd like to see us get to the point where we could describe barrels in terms of relative stiffness..when referring to tuner, at least...and length affects stiffness faster than contour or barrel od. I've also mentioned on here about having done as Boyd has mentioned...thinning a section of the barrel at some point behind the tuner. I firmly believe that wide tune windows and "tunability", for lack of a better word.. has a whole lot to do with barrel stiffness and that stiffer isn't necessarily better. The same likely can be said without a tuner..just not as apparently...particularly on the vertical plane as the tuner induces a vertical bias.

Something that I want to try, is to put a fixture that will accept a barrel in a vise and measure deflection with an indicator, before and after machining a thinned area of barrel, without and with a tuner or weight...respectively..at different lengths. I'd want to get the deflection equal and try tuning, side by side. I feel like they would respond similarly, but wonder what the affect of the unaltered portion of the barrel might have vs. the barrel at the same deflection, but longer. Obviously, velocity gained/lost would be a factor, too.
 
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