Tuner Pictures

A

AVanGorder

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Let's see them "Tuners"
Here is the tuner Hal Drake made and installed on his HV 30BR.
Tuner.jpg
 
I am new to benchrest shooting and learning quickly. As a retired engineer I do understand barrel harmonics (resonances). What is the "tuner" supposed to do to improve accuracy? Dampening, shift resonance, or what?
 
Lynn said:
Rangerat its a shame Boyd took the time to post you off line but didn't post it here.As a SuperModerator one would think he has a certain immunity to the hostilty surrounding certain tuner types.

A standard everyday tuner will help you keep shooting small groups as the conditions change.It requires constant adjustment to keep things small.

The controversial tuner that nobody has anything good to say about doesn't need to be adjusted all day.The whole concept of how this tuner works is 3 months old on this forum.The standard twist all day tuner has been around forever and according to Mike Marcelli was invented by Mr Rose.

If your a Engineer here is how I see it.
When you send a signal down a piece of waveguide it is a wave.To get maximum pwer transfer you want the least amount of reflected or returned wves coming back at your outgoing signal.Voltage Standing Wave Ratio or VSWR.On a typical circuit like a typical bench gun we want a VSWR of 2 to 1 and we use tuning stubs on our waveguide to reduce the unwanted or reflected waves to improve our VSWR and get the best possible signal and maximum power transfer.

With the Bill Calfee type tuner that has gotten everyones panties in a wad we are looking not for a 1.5 VSWR but a 1.0 VSWR ratio so we don't have any of the nasty stuff hurting our signal.As he is arguably the best rimfire gunsmith in the world and he guns win everything using his muzzle devices it seems he has it pretty well dialed in.
The big rub comes in when people ask for a simple formula for tuning VSWR without ever looking at a stripline or waveguide.It as you know is for the most part trial and error done by a technician sitting at a bench all day looking at his analyzer or using his sliding short.
When he doesn't explain it as an engineer would he is criticised and then doesn't post for awhile extending the learning curve to those who are actually interested.
Lynn
Click to expand...

So Lynn, I guess your calling the first tuner pictured in this thread a standard, everyday tuner? Thats fine, it is a very simple tuner and one that I designed to put about 6 ozs out in front of the muzzle. However, I can assure you that that tuner never changes position on that gun, and yes I do pre-load for it. Does it stop the muzzle, heck I don't know. But it won't put loads from two different velocities into the same hole. It does shoot OK though.
 
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Lynn,
Your wave guide barrel parallel intrigues me. My first experience with a tuner (one of Jackie's, pre rubber and brass) was with a stepped barrel. Coming back from the muzzle, there was a 15/16 dia. section, a little over 6" long, a right angled step up amounting to approximately .1 in diameter, another slightly more than 6" cylindrical section, and then a similar step up to the original contour. Total barrel length was about 21.5 from the bolt face. After the fact it has occurred to me that there may be functional advantages to a stepped barrel. In this case, I had it done to take off weight without too much effort. It was a well used barrel. Could the steps have an attenuating effect?
 
Rangerat

The pictures Scott D posted is my design. It is one piece, mounts on 2 inches of 36 tpi on the barrel, weighs about 5.5 ounces, and does possess a dampenning feature. The only thing I can say about it's affectiveness is I have done OK in Competition using it.......jackie
 
Lynn said:
Rangerat its a shame Boyd took the time to post you off line but didn't post it here.As a SuperModerator one would think he has a certain immunity to the hostilty surrounding certain tuner types.

A standard everyday tuner will help you keep shooting small groups as the conditions change.It requires constant adjustment to keep things small.

The controversial tuner that nobody has anything good to say about doesn't need to be adjusted all day.The whole concept of how this tuner works is 3 months old on this forum.The standard twist all day tuner has been around forever and according to Mike Marcelli was invented by Mr Rose.

If your a Engineer here is how I see it.
When you send a signal down a piece of waveguide it is a wave.To get maximum power transfer you want the least amount of reflected or returned waves coming back at your outgoing signal.Voltage Standing Wave Ratio or VSWR.On a typical circuit like a typical bench gun we want a VSWR of 2 to 1 and we use tuning stubs on our waveguide to reduce the unwanted or reflected waves to improve our VSWR and get the best possible signal and maximum power transfer.

With the Bill Calfee type tuner that has gotten everyones panties in a wad we are looking not for a 1.5 VSWR but a 1.0 VSWR ratio so we don't have any of the nasty stuff reflecting back and hurting our signal.As he is arguably the best rimfire gunsmith in the world and his guns win everything using his muzzle devices it seems he has it pretty well dialed in.
The big rub comes in when people ask for a simple formula for tuning VSWR without ever looking at a stripline or waveguide.It as you know is for the most part trial and error done by a technician sitting at a bench all day looking at his analyzer or using his sliding short and placing compacitive stubs along the path.
When he doesn't explain it as an engineer would he is criticised and then doesn't post for awhile extending the learning curve to those who are actually interested.
Lynn
Click to expand...

Thanks Lynn,

I was thinking more in the direction of barrel resonances and find your explanation of it using transmission line theory very interesting.

There should be a reasonable physical analysis showing how tuners match the barrel characteristics to absorb the traveling wave along the barrel. Has someone calculated the propagation of the wave with regard to the interaction with the projectile moving down the barrel simultaneously. Whether the wave is at the muzzle first or not, there is interaction between the wave and the projectile.

Has anyone calculated the impedance of the barrel transmission line with the intent to match the tuner to absorb the energy?

There might be some prior analysis that has been done for maximizing accuracy of large military guns. If so, it might be applicable scaled down.

Ed
 
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