How a tuner works

lcw said:
You fellers are a tough crowd when it comes to determing a persons knowledge of how competition works when asking questions.

I am just getting into the competition, last year I finished my first full year of matches in St. Louis. The biggest shoot I have participated in to this date is the East/West in St. Louis last year. I have sent in my entry and hope to be one of the shooters at this years Shamrock, plan to travel to Kansas City for some shoots with friends I have made to this point, will shoot the schedule for St. Louis, and am considering some National participation later in the year. I own a BAT model B and a DS both in Leonard stocks, LCS 45X scopes, enjoy shooting a bunch, and want to learn all I can. Thanks for the information.

How does the smaller contoured barrel take to heat and does it effect one's ability to shoot fast versus the hunt and peck style of shooting???

Linc
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Linc, welcome to the fray. It is a fun ride. Hope to meet you at the Shamrock. Sent my money Monday.

You'll love the Leonard stocks. Terry lives just 15 minutes from me.

As to heat in a thinner barrel, if the barrel is stress free heat is not a problem. That is not to say you can't burn one out though. You will find that barrels are like the rear tires on a rail dragster...expendable.
 
Shelley

The best approach in my humble opinion is to hire a piano tuner.Take a blank to the piano tuner and let him ring it and mark the barrel.Once the barrel is marked determine the distance to the end of the barrel and its weight.Multipy by 1.5 and if you can make weight your all set.If you can't make weight sell the barrel and get a new one.
A piano tuner will hit the node very quickly and understands everything Bill Calfee is talking about.He might call it the 3rd octave instead of the parrallel node but who cares what its called.
I tuned high frequency electronic waves for 22 years and you can hit the same point 3 different ways.The first way is alot of weight before the node.The second way is alot of weight after the node.The 3rd way is the right amount of weight absolutely in the middle of those two points.
Lynn
 
Varmit Al

Al in your included page I see you have some frequencies listed.One of them is 134.5 Hz.
If we double that frequency to get the second harmonic we get 269 Hz I see in your examples several natural frequencies that are extremely close to a second,third or fourth harmonic.As you know the third harmonic is often very large.I rarely see a natural fequency that close to a harmonic when doing electronic work with waves.
Lynn
 
The vibration mode described here is what occurs AFTER the bullet has left the barrel. It is simply the NATURAL vibration that occurs in all barrels, or bars, when they receive a suddenly applied. and then quickly removed force. In other words you hit or strike the barrel with something. You could do it with a pen or it could be done with a bullet. The shape the bar takes on as it vibrates naturally is described in all physics books and was demonstrated very well by Varmint Al. The vibration pattern will almost always contain a node about 2/3 up the length of the barrel towards the muzzle. The node is a point of minimum lateral motion but it is not zero. The node is the point of maximum angular motion.

Varmint Al's analysis is of vibration that occurs in the whole gun, including the barrel, as a result of the recoil force applied to the face of the bolt. It does not include the force applied by the bullet to the barrel. Whether this bullet force is significant is debatable - some think it is, some don't. Both the recoil effect and the bullet effect are less in rimfire than in centerfire simply because of the forces involved

This vibration that occurs while the bullet is in the barrel is called FORCED vibration. It may or may not take on the same form as natural vibration. It may contain a node or not. It may even contain several nodes. So far I don't think anyone has really proved what vibration pattern exists in the barrel as a result of the forced vibrations from the bullet. It is however the vibration that is taking place BEFORE the bullet exits and thus the only vibration that effects bullet flight. The vibration in a barrel resulting from recoil or bullet effects is mostly in the vertical plane but it will in some guns also occur in planes out of the vertical - this is just impossible to predict. The reason it can't be predicted is because the bullet effect is a result of barrel curvature, and this is very difficult to measure. Probably in most barrels the plane of vibration changes with each vibration cycle.

The effect of a tuner is to change the point in the vibration at which the bullet leaves the muzzle such that you get more consistent lateral velocity or a more consistent angle of departure. The degree of lateral velocity and angle of departure are both determined by just how the barrel is vibrating at the muzzle when the bullet departs. The point at which the bullet leaves the muzzle, which is effected by bullet velocity, is what is most affected by the tuner. A tuner gets it's primary effect by simply adding weight to a barrel. A secondary and lesser effect can be achieved by moving the weight
 
pacecil,

Thank you! Finally someone else has figured out there is a difference between dynamic and residual vibrations. Now the real question how can these forces be modeled. I do understand pressure vessels, and a barrel with a bullet running down it even at 22 speeds is a very dynamic pressure vessel. As the bullet will cause besides vertical and horizontal motion of the muzzle it will also induce radial motion too. I’m sure that these motions are not being taking into account right now. But I don’t have the knowledge or the software to model this. There must be a way to use FEM to do this, which might also lead to a formula which would get us a real starting point. It would really be nice if could be done, so we wouldn’t have to resort to all of this trial and error tuning. Any ideas?

Best,

Roger
 
RvA said:
pacecil,

Thank you! Finally someone else has figured out there is a difference between dynamic and residual vibrations. Now the real question how can these forces be modeled. I do understand pressure vessels, and a barrel with a bullet running down it even at 22 speeds is a very dynamic pressure vessel. As the bullet will cause besides vertical and horizontal motion of the muzzle it will also induce radial motion too. I’m sure that these motions are not being taking into account right now. But I don’t have the knowledge or the software to model this. There must be a way to use FEM to do this, which might also lead to a formula which would get us a real starting point. It would really be nice if could be done, so we wouldn’t have to resort to all of this trial and error tuning. Any ideas?

Best,

Roger
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Check the index section, Varmint Al has modeled almost all the significant contributing factors;

http://www.varmintal.com/apres.htm
 
Jerry & Dave,Jerry,I was out clearing the 2 driveways of snow,i missed your call,THe easy way on the Harrells is to thread the tuner onto the barrel & take the ball plunger out & install a 10/32 set screw ,mine has 2 set screws ,one from each side,it has never moved. BILL
 
I have been messing with tuners ever since Jackie started beating me with them. My down fall in benchrest has always been tune. I thought if something would help, I was going to try it. Being an unknown area with not a lot of factful proof, I made several different tuner designs. My findings are as follows: These things are dampners and not tuners. Do they work: yes
are they easy to set and use: no!

My findings are the same as Shelley and Bill Meyers. I do exact as Bill has said. When I finally find the perfect setting, I never touch the tuner again. These things are wonderful when you find that perfect spot.

All of my good shooting barrels have the tuners protruding past the muzzle. Also, tuners have to be firmly attached.

I do not make simple adjustments, one to two turns at a time til the verticle is gone.
 
I'm pretty OK with how to go about finding the sweet spot on any given tuner. But once I find the sweet spot on any given tuner it may not be "THE SWEET SPOT" for that barrel. Maybe the tuner is too heavy or even too light.

How does one go about determining what weight tuner is the right weight tuner? Is there a way other than starting with a "real light" tuner .... going from 0 - 500, adding some weight, going from 0 - 500, adding some more weight .... and so on.

Some people talk about ringing barrels ... other don't believe in ringing barrels but they somehow have a way to figure out the right weight for their tuner ....

Bill Meyer's, I remember in a 6mmbr article it was mentioned that you don't believe in ringing a barrel / rifle .... how do you go about it?

What about Gene Beggs .... you talked about experimenting with different weight tuners ... so you must have a method.

Or Shelley .... how do you go about it?

How to figure out the weight needed for any given barrel / rifle would be a tremendous help that would save lots of people lots of the expensive ammo.

If anyone is willing to share their method it would be great.

I'm sure it would be a big help and appreciated by many.

Fred
 
Best kept secret

Fred:
I guess will have to just wait for the next issue. I've been shooting for too many years to count, and I still have trouble understanding the weight issue. When I add extra weight, I have to buy bigger gun cases. After I get the larger/longer cases, I have to buy a bigger truck. It never ends.
 
Mike Swartz said:
Question??? Is one to believe that the "track" of the muzzle is strictly vertical?? Or is the "stopping" of the muzzle a multi-axial thing? If the "track" of the muzzle is not circular how does the tuner compensate for the ovality of/ or the ecliptic trace of the Muzzle??

Mike Swartz
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Mike, no one else has answered your question and it's a very good one so I'll do my best.

No, the 'track' of the muzzle is not strictly verticle. If there is any curvature in the horizontal plane after the barrel is installed on the receiver, that will cause vibration in the lateral plane when the barrel is fired and it is very unlikely that the stop of the barrel in the lateral plane will coincide with that of the vertical. Such a barrel cannot be tuned, if you get the verticle out, you have horizontal dispersion; if you tune the horizontal out you have verticle. "So what's the answer?" Re-clock the barrel on the receiver so as to hide the curve in the verticle plane with the muzzle drooped to its lowest point.

Gene Beggs
 
Fred

I'm not an engineer and I don't have any science to find the ideal weight for a tuner. The 6-6.2oz weight of my tuner is simply about the maximum that a light varmint can stand if it's a bit light to begin with. It's easy to add weight to either my tuner or Gene's. Simply part off a piece of bar stock that has the appropriate hole bored in the center. Then you sandwich it between the two threaded weights.

I wish I could be more help but I simply don't know the optimum's on tuners.

Shelley
 
Gene Beggs said:
Mike, no one else has answered your question and it's a very good one so I'll do my best.

No, the 'track' of the muzzle is not strictly verticle. If there is any curvature in the horizontal plane after the barrel is installed on the receiver, that will cause vibration in the lateral plane when the barrel is fired and it is very unlikely that the stop of the barrel in the lateral plane will coincide with that of the vertical. Such a barrel cannot be tuned, if you get the verticle out, you have horizontal dispersion; if you tune the horizontal out you have verticle. "So what's the answer?" Re-clock the barrel on the receiver so as to hide the curve in the verticle plane with the muzzle drooped to its lowest point.

Gene Beggs
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Gene
Can you tell us your technique for making sure the barrel is indexed so the curvature is in the verticle plane?
James
 
Chisolm said:
Gene
Can you tell us your technique for making sure the barrel is indexed so the curvature is in the verticle plane?
James
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James, I made up a faux receiver of aluminum threaded exactly like the action. Once the barrel is partially chambered and tenon threaded, I place the faux receiver in the chuck and indicate it in, then take a light skim cut off the face so it's running true to the lathe bed. Then screw the barrel in and tighten just snug. Place a dial indicator against the muzzle of the barrel and slowly rotate the spindle. You will quickly locate the position of the barrel that wants to be clocked up at six o'clock. Mark this in some way. I wrap a piece of masking tape around the barrel and mark this spot with a pencil.

Now, take the barrel out of the lathe and screw it into the receiver that it will be installed on and tighten it up. If you are lucky, the mark you made will be on the bottom of the barrel in the six o'clock position relative to the receiver. But if you're like I am, the darn thing will probably be somewhere else. :rolleyes: Let's say the mark is at nine o'clock. This will make it necessary to rotate the barrel 90 degrees clockwise to line it up. If the barrel is threaded 1.063 X 18, you will need to remove .0137 from the tenon shoulder. This should then put the mark at six o'clock. Hope this makes sense. I'm gettin' tired; think I'll call it a night.

Gene Beggs
 
Gene Beggs said:
James, I made up a faux receiver of aluminum threaded exactly like the action. Once the barrel is partially chambered and tenon threaded, I place the faux receiver in the chuck and indicate it in, then take a light skim cut off the face so it's running true to the lathe bed. Then screw the barrel in and tighten just snug. Place a dial indicator against the muzzle of the barrel and slowly rotate the spindle. You will quickly locate the position of the barrel that wants to be clocked up at six o'clock. Mark this in some way. I wrap a piece of masking tape around the barrel and mark this spot with a pencil.

Now, take the barrel out of the lathe and screw it into the receiver that it will be installed on and tighten it up. If you are lucky, the mark you made will be on the bottom of the barrel in the six o'clock position relative to the receiver. But if you're like I am, the darn thing will probably be somewhere else. :rolleyes: Let's say the mark is at nine o'clock. This will make it necessary to rotate the barrel 90 degrees clockwise to line it up. If the barrel is threaded 1.063 X 18, you will need to remove .0137 from the tenon shoulder. This should then put the mark at six o'clock. Hope this makes sense. I'm gettin' tired; think I'll call it a night.

Gene Beggs
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Thank you Gene. I sure appreciate all your help.

James
 
Gene,

When I read about people indexing a barrel most times they shoot a group, rotate the barrel 90 degrees, shoot another group, rotate the barrel 90 degrees, and so on until they find the position that the barrel shoots best in.

Is the indexing that you are talking about and the way you do it using a dial indicator actually doing the same thing without having to shoot groups?

Fred
 
BigMacky said:
Gene,

When I read about people indexing a barrel most times they shoot a group, rotate the barrel 90 degrees, shoot another group, rotate the barrel 90 degrees, and so on until they find the position that the barrel shoots best in.

Is the indexing that you are talking about and the way you do it using a dial indicator actually doing the same thing without having to shoot groups?

Fred
Click to expand...

Exactly.

Gene Beggs
 
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