Moderator as barrel tuner

[1066]

2 hours ago, Popsbengo said:

The first link is an excellent if somewhat technical read.  I note  the quote:  "It should be noted that Calfee's theories have absolutely no basis in fact and are mathematically untenable. But that does not stop it being the most quoted work in the popular press on barrel vibrations and the tuning of barrels."    Pretty much as Brown Dog described earlier.

It seems to me that it's pretty common in shooting that someone stumbles onto an idea or method and gets results by experimenting (which is laudable) but then tries to back-engineer an explanation without either sufficient knowledge or scientific experimentation.  Unfortunately that's then taken up by a community of non-experts and becomes dogma.  Like many of the most favoured load development techniques (IMHO of course) lacking in any kind of statistical rigour, drawing conclusions from way to small data samples and uncontrolled variables.

 

It's true that many of Calfee's ideas lack mathematical analysis, however, it can't be overlooked that Calfee built rimfire rifles have won more regional, state, national and world benchrest records than any other, all of course fitted with his tuners. All the common tuners now in use, and just about all competitive rimfire benchrest shooters use them, whether it's a Harrell, Grunig & Elmiger,  Ezell or other, all stem from his work.

[Popsbengo]

2 hours ago, 1066 said:

It's true that many of Calfee's ideas lack mathematical analysis, however, it can't be overlooked that Calfee built rimfire rifles have won more regional, state, national and world benchrest records than any other, all of course fitted with his tuners. All the common tuners now in use, and just about all competitive rimfire benchrest shooters use them, whether it's a Harrell, Grunig & Elmiger,  Ezell or other, all stem from his work.

I think you miss my point;  I did say practical experimenting is laudable, clearly Mr Calfee has success - good on him.  I was making the general point that some experimenters in the shooting community can't resist creating a 'back story' to underpin their experimental findings. It's not scientific or good engineering and therefor adds little to the understanding of the physics.  It can however be very successful as in Calfee's example.

[Ronin]

Certainly a place for tuners

They work and its surprising how incrementally small the ajustment is required to get a barrel to "group" well once a decent load is found, its relatively easy to make that smaller

Ive made my own Tuners for my own rifles several times using simple fine thread and o rings designed in to prevent unwanted adjustment

 

[1066]

This type design might be worth experimenting with. (not mine, just grabbed the picture). The theory is, you set the coarse adjustment by moving the whole thing fore and aft, then rotate the off center mass to tune out lateral error then fine tune vertical error with the micrometre adjustment.

What I would like to see is experiments carried out on the Eley test range or similar tunnel range under controlled conditions. Each lot of Eley rimfire is tested through four different barrels in fixed rests at 50m and groups electronically measured, then all groups (200 shots) combined to give an overall groups size. Until recently you could enter the lot number, found on the side of your box of ammo and find the test results for that exact lot.

https://eley.co.uk/find-the-perfect-batch-with-eleys-lot-analyser/

 

 

[brown dog]

21 hours ago, 1066 said:

 

https://www.varmintal.com/atune.htm

Thanks - good links; surprised to see how little is known rather than 'assumed'.

Interesting that both articles seem to agree  that the tuner's effect on line of departure is the dominant effect (as opposed to the velocity of the muzzle movement itself).

Still none the clearer where the tuner best sits or why - empirically, most seem to have the mass forward of the muzzle, but some (EC and Kolbe's experimental mass) are behind.

 

 

 

[brown dog]

5 hours ago, 1066 said:

 

https://eley.co.uk/find-the-perfect-batch-with-eleys-lot-analyser/

 

 

 

Just had a look at that too. 

The 50m machine rest Tenex targets tell us a lot with regard to our other chats about the realities of .22!

[1066]

28 minutes ago, brown dog said:

 

Just had a look at that too. 

The 50m machine rest Tenex targets tell us a lot with regard to our other chats about the realities of .22!

 

Indeed - when you think this is with world class ammunition, shot under perfect conditions in match quality, regularly maintained barrels, it puts the "My 10/22 shoots 1" groups at 100yds with HP's all day long" into a bit of perspective.

And I have to say - when checked through the lot analyser, I don't find some of the lots of Eley Match and Tenex all that impressive.

[brown dog]

8 hours ago, 1066 said:

, it puts the "My 10/22 shoots 1" groups at 100yds with HP's all day long" into a bit of perspective.

😂 yes!

[Ronin]

There is information there, Tuners work just as well in centerfire application ads they do rimfire.

 

Many of the F Class shooters (myself included) use tuners 

 

EC Tuners (Eric Cortina- a top level USA team member for example have been in production and use for years)

 

Simple design, fine ajustment

 

Works

[Big Al]

On 11/19/2020 at 10:06 PM, brown dog said:

 

Just had a look at that too. 

The 50m machine rest Tenex targets tell us a lot with regard to our other chats about the realities of .22!

The thing I dont understand about batch testing ammo is the concept of securing the action in a vice that has zero movement, this doesnt seem to replicate how the gun will be shot and in turn how the harmonics will perform in the real world. Considering some rifles can be tuned with stock bolt adjustment it seems counter intuitive to lock it in a vice and allow zero movement.

Then again I accept these guys know far more about it than me.

 

[Popsbengo]

26 minutes ago, Big Al said:

The thing I dont understand about batch testing ammo is the concept of securing the action in a vice that has zero movement, this doesnt seem to replicate how the gun will be shot and in turn how the harmonics will perform in the real world. Considering some rifles can be tuned with stock bolt adjustment it seems counter intuitive to lock it in a vice and allow zero movement.

Then again I accept these guys know far more about it than me.

 

This is the whole problem to me.  Eley are trying to demonstrate their ammo is consistent in a jigged up system, ie taking away all (?) of the other factors so as to isolate the one set of variables - ammunition alone and not ammo/rifle/environment/shooter combined.

It's useful data but not definitive in my mind because for the very reason it's not about the real-world combined results.  But one has to start somewhere.  If we had perfect ammo then all efforts could be directed to the firearm and shooter variables.  Part of the issue is that with less than perfect ammo harmonics can, in certain circumstances, achieve better results due to the factors best described in the papers cited earlier.   That stated, it's still best to have near perfect ammo - it's what we reloaders strive for.  If an harmonic tuner can aid precision, all the better.

It's a fascinating subject.

 

[1066]

5 minutes ago, Big Al said:

The thing I dont understand about batch testing ammo is the concept of securing the action in a vice that has zero movement, this doesnt seem to replicate how the gun will be shot and in turn how the harmonics will perform in the real world. Considering some rifles can be tuned with stock bolt adjustment it seems counter intuitive to lock it in a vice and allow zero movement.

Then again I accept these guys know far more about it than me.

 

I must agree, with all the millions of .22lr ammunition produced and all the money spent on R&D over the years, it does seem pretty basic to just clamp a barrel/action in a solid vice. The Ransom rest use for pistol/ammunition testing seems the right idea and gave very good results.

[brown dog]

I'm not sure I understand the thinking behind introducing other variables - then the test isn't testing the ammo alone; it's testing the other variables too - and it wouldn't be possible to split the effectors out. 🤔

 

...anyway... we all 'get' that the tuners affect some aspect of barrel vibration. But no one is quite sure how barrels move - multiple vibration modes happening simultaneously...  and the unanswered prize question is what does the tuner actually do? What's the primary effect delivering accuracy: Is it changing frequency of a harmonic? Moving nodes? Or just a damping effect?

And... how does that answer chime with positioning relative to the muzzle? Beyond or behind?

[Big Al]

30 minutes ago, brown dog said:

I'm not sure I understand the thinking behind introducing other variables - then the test isn't testing the ammo alone; it's testing the other variables too - and it wouldn't be possible to split the effectors out. 🤔

 

Recoil itself plays its part in how a rifle shoots because it changes the harmonics within the system and certainly in centerfire rifles zero recoil has been proven to have a detrimental effect on accuracy. You couldn't attach a heavy recoiling rifle to a fixed vice and expect good results, its been shown not to work.

When I built my BR heavy gun it weighed 46lb with an 8" wide forend and a 3" wide rear, both sat on/in sand filled bags. A combination of the weight and the friction meant with a 6 Dasher case firing a 105 bullet the gun would recoil about 1" when left to free recoil backwards. The whole shooting system was extremely stable and almost impossible to shoot badly unless you broke certain rules.

One of this rules was recoil management. The same amazingly accurate gun would go to pieces if you slid your shoulder in tight and tried to restrict the already minimal recoil, I tested his extensively. Because of the lack of recoil it really needed to be left to do its thing, the minute you made any contact with the gun it didn't shoot as well. There are examples from the US of heavy guns being 90lb and firing calibers like 6BR, the initial idea was to almost try and eliminate recoil to make the gun easier to shoot but it didn't work, the guns shot better with an element of recoil to be allowed in the system. 

I appreciate the .22LR is a much smaller case and the harmonic pattern will be different but I still wonder how batch testing in a vice makes sense when the BR rimfire shooter will still let the gun recoil freely albeit not very far?

If I was going to batch test in a tunnel I would contruct a sled system that would hold the gun perfectly still and repeatable but would allow recoil to take place and also be controlled and adjusted as required, something like a rail gun.

[1066]

4 minutes ago, Big Al said:

 

If I was going to batch test in a tunnel I would contruct a sled system that would hold the gun perfectly still and repeatable but would allow recoil to take place and also be controlled and adjusted as required, something like a rail gun.

This seems such an obvious and easy way forward I can't believe that it's not the way Eley test their ammunition. As far as I know the Lapua .22 test facility use a "return to battery" set-up. It would be interesting to compare results.

[1066]

46 minutes ago, brown dog said:

I'm not sure I understand the thinking behind introducing other variables - then the test isn't testing the ammo alone; it's testing the other variables too - and it wouldn't be possible to split the effectors out. 🤔

 

...anyway... we all 'get' that the tuners affect some aspect of barrel vibration. But no one is quite sure how barrels move - multiple vibration modes happening simultaneously...  and the unanswered prize question is what does the tuner actually do? What's the primary effect delivering accuracy: Is it changing frequency of a harmonic? Moving nodes? Or just a damping effect?

And... how does that answer chime with positioning relative to the muzzle? Beyond or behind?

The way I see it, the extra mass should be in front of the muzzle - the further out the less weight required to do the same job. There seems to be different approaches, for example to tune for positive compensation. This is not a new idea, a Fulton regulated No 4 .303 target rifle was "tuned" for positive compensation, the idea being that the bullet should exit the muzzle on the upward travel of the vertically vibrating barrel. The theory is that a slightly faster bullet will exit earlier on the up swing and depart on a lower trajectory and a slower bullet will exit later for a higher trajectory - If the rifle was regulated for 600 yards the two trajectories should cross at that distance and give minimum vertical dispersion. Remember Reynolds and Fulton were regulating .303 service rifles with thin barrels shooting selected service issue ammunition, mainly by various amounts of pressure bedding.

This idea is seems to be one of the primary aims for rimfire benchrest shooting - Where you have no control over the velocity of the ammunition you will have vertical error at competition distances.

The alternative idea is that you get the bullet to exit the muzzle while it's at a "stopped" position, either at the top or bottom of a vibration or even at the center of a figure eight sinusoidal pattern. 

[brown dog]

I happy with all the theories - just rather bizarre that the tuning mechanism seems unknown and nearer alchemy than physics. 

Muzzle position:  I'm quite struck that one of the en vogue tuners (EC?) is behind the muzzle.  Difficult to say where is right if no one actually knows what's happening! 😂😊 

Machine rests for .22?  Looking at Lapua tgts, from a quick Google, they don't strike me as any different to the Eley. 

[Mark II]

As I am still doing load development for my 308 I will start with experimenting with my .22 Tikka T1x with the  mod and shim washers just for the hell of it. 

But first I will put it in my Oryx chassis I have just ordered.

 

 

[Big Al]

5 hours ago, brown dog said:

I happy with all the theories - just rather bizarre that the tuning mechanism seems unknown and nearer alchemy than physics. 

Muzzle position:  I'm quite struck that one of the en vogue tuners (EC?) is behind the muzzle.  Difficult to say where is right if no one actually knows what's happening! 😂😊 

 

 

Your looking too deeply BD.

I think both myself and Alan have already said it doesnt matter where exactly the tuner is placed, it just means more or less weight shift needs to occur to get the same results. The EC tuner is popular but personally I think its too heavy in combination with the thread making for too coarse adjustments.

I fitted one recently and also shortened it by about 40% to bring the weight down to work better with the thread that we have to work with. This ives better control of the incremental adjustments and you can see more of whats going on. There are other aspects of the design I dont like as well as its weight to thread pitch ratio but its not a thread about whats wrong with the EC tuner so I will keep them to myself.

Ive had tuners in front and behind the crown and also mid barrel, they have all worked as good as each other but required different amounts of weight to get the job done. Mid barrel is pointless it just adds too much weight and looks ugly. Around the muzzle is the right place.

[Big Al]

7 hours ago, 1066 said:

There seems to be different approaches, for example to tune for positive compensation.

Im sure you will know positive compensation can be done with both a tuner and varying charge weights and seating depths, Ive done a lot of the later.

I remember when I told people about me tuning for positive compensation at 600yds and 1000yds they looked at me like I had two heads, it works just fine.

[Mark II]

12 hours ago, Big Al said:

Your looking too deeply BD.

I think both myself and Alan have already said it doesnt matter where exactly the tuner is placed, it just means more or less weight shift needs to occur to get the same results. The EC tuner is popular but personally I think its too heavy in combination with the thread making for too coarse adjustments.

I fitted one recently and also shortened it by about 40% to bring the weight down to work better with the thread that we have to work with. This ives better control of the incremental adjustments and you can see more of whats going on. There are other aspects of the design I dont like as well as its weight to thread pitch ratio but its not a thread about whats wrong with the EC tuner so I will keep them to myself.

Ive had tuners in front and behind the crown and also mid barrel, they have all worked as good as each other but required different amounts of weight to get the job done. Mid barrel is pointless it just adds too much weight and looks ugly. Around the muzzle is the right place.

I am guessing that the compensator has a locking nut to get the orientation correct wouldn't that have the same affect as a tuner or isn't there enough mass to it?

[Shuggy]

9 minutes ago, Mark II said:

I am guessing that the compensator has a locking nut to get the orientation correct wouldn't that have the same affect as a tuner or isn't there enough mass to it?

No, the EC tuner and indeed most of the other designs use nylon tipped grub screws to control the friction on the thread.

[Mark II]

4 hours ago, Shuggy said:

No, the EC tuner and indeed most of the other designs use nylon tipped grub screws to control the friction on the thread.

Sorry what I meant was could the compensator be used as a tuner as it can be set at different distances using the lock nut although you couldn't fine tune obviously 

[Shuggy]

1 hour ago, Mark II said:

Sorry what I meant was could the compensator be used as a tuner as it can be set at different distances using the lock nut although you couldn't fine tune obviously 

Apologies for my misunderstanding. I suppose that you could, but wouldn't it rather negate the whole point, which is to have a graduated scale, allowing you to fine tune the position?

[Big Al]

7 hours ago, Mark II said:

I am guessing that the compensator has a locking nut to get the orientation correct wouldn't that have the same affect as a tuner or isn't there enough mass to it?

The muzzle brake needs to stay in the orientation its currently in to work properly, you dont want gases exiting downwards or it will cover you in dust and also try to lift the muzzle of the ground when shooting prone. Thats the reason there is a tuner fitted behind it. Also the muzzle brake is too heavy and has no means of making small accurate and repeatable movements which a good tuner needs to be able to do.

I did use a pepper pot muzzle brake as a tuner once, that worked but it had the correct thread and the nylon tipped set screws and fine increments so it was very much a tuner with a brake incorporated.