More on Barrel Tuners

Get or give advice on equipment, reloading and other technical issues.

Moderator: Mod

Message
Author
sungazer
Posts: 113
Joined: Fri Mar 17, 2017 7:58 pm

Re: More on Barrel Tuners

#136 Postby sungazer » Sat Jun 02, 2018 8:16 am

Thanks willada I would really like to keep the conversation going but I can see that written correspondence has its limitations. To get into the detail it really requires verbal and a whiteboard and perhaps some instrumentation and practical experiments / demonstrations.

wsftr
Posts: 52
Joined: Tue Jan 30, 2018 12:58 pm

Re: More on Barrel Tuners

#137 Postby wsftr » Sat Jun 02, 2018 8:45 am

what is coning and how does it matter?

Is it just me or do those groups look like there is virtually no "width" from one setting to another? i.e. how sensitive to any one change (change could be environmental or a component tolerance) is it?
How did the rubber hit the road - i.e. what was the average vertical for anyone distance 300 - 1000 for the load or settings selected.
I'm interested as an approach that develops a tune without a tuner and then again with a tuner is a high round count for just the theoretical aspect - it then has to be taken into the cauldron of competition to see how it plays out.
"Plays out" uses hind sight to look back at vertical over a season. If the vertical isn't better than previous approaches then it gets difficult to understand how the approach helped.

pjifl
Posts: 602
Joined: Fri Jun 17, 2005 12:15 pm
Location: Innisfail, Far North QLD.

Re: More on Barrel Tuners

#138 Postby pjifl » Sat Jun 02, 2018 2:10 pm

Gyro,

You can do much better than 'Peer Review' despite who is involved.

Peer review has been debased by many called 'Scientists'. You scratch my back - I scratch yours.
So both get more published papers and bring in more research money. Or these days often Advertising Money !

In one word, Science is about repeatability. Reliable replication by an experimenter and by others elsewhere after accurate descriptions of the methods used.

Much so called 'science' these days has been found seriously wanting.

For example, drug companies have found that at least half of the so called 'science' published in respectable medical Journals cannot be replicated.
So half of this so called Science is Bullshit Science. It just aint science.
A recent review has showed how much so called 'Forensic Science' is Bullshit Science.

I have changed my definition of 'Scientist'. It has nothing to do with who belongs to what big name organization and little to do with so called 'qualifications'.

'SCIENTISTS ARE PEOPLE WHO HONESTLY PRACTICE THE SCIENTIFIC METHOD'.

How can you do better ? Simply by designing an experiment carefully and measuring the muzzle Velocity.
You will need to measure the precision of the instruments you use - which can be done.
Then repeating the experiment a few times and being honest with the results.
Finally, by having others confirm your experiment PREFERABLY WITH THEIR OWN EXPERIMENTS.

Science is also a work in progress. It is NEVER finalized. It is being refined all of the time.

For example, the mass of the projectile used in any recoil momentum calculation should have added to it about half of the mass of powder used.
I personally think the difference in Muzzle Velocity of free or rigidly restrained rifles is still much lower than some have suggested.

But the 'SCIENTIFIC' way to find out is to go back to basic experiments and measurements and match the results to theory. Not just 'Peer Review' ideas.

Peter Smith.

Gyro
Posts: 349
Joined: Sat Jun 10, 2017 2:44 pm
Location: New Zealand

Re: More on Barrel Tuners

#139 Postby Gyro » Sat Jun 02, 2018 4:19 pm

Seems we see things differently Peter. I have had an interest and an understanding ( my understanding ) of the "scientific method" for a very long time.

My words were strong. Probably too strong for this site.

Regards Rob Kerridge.

Gyro
Posts: 349
Joined: Sat Jun 10, 2017 2:44 pm
Location: New Zealand

Re: More on Barrel Tuners

#140 Postby Gyro » Sat Jun 02, 2018 5:51 pm

Apologies if i was too harsh here. Or too OTT. I is what i is and i need a break. I knew it was coming !!!

All good. Regards from a mad inventor.

williada
Posts: 712
Joined: Wed Jul 22, 2009 12:37 am

Re: More on Barrel Tuners

#141 Postby williada » Sun Jun 03, 2018 11:38 am

wsftr you can't get Harold Vaughn's book Rifle Accuracy Facts these days but on page 183 and 184 he has some useful diagrams as does Brian Litz Applied Ballistics for long range shooting p 156 with regard to gyroscopic bullet stability. Or go to Nennstiel

http://ffden-2.phys.uaf.edu/212fall2001 ... /index.htm

I've put diagrams up before but must have wiped them. If you can imagine a bullet flying along in a corkscrew motion along its trajectory. The corkscrew motion is belled for about 200 yards or looks like an ice cream cone at the start of the trajectory until high frequency vibrations damp out. For practical purposes this is about 140 yards. I choose 140 yards because the group opens up to see its lay pattern on the axis of shots in the group for micro analysis more so than lift for macro analysis purposes. Wind is relatively insignificant as is light etc as trade offs.

The projectile starts off with high frequency coning motions or corkscrew imparted from the rifling with the projectile vibrating like a waving nose and tail of a javelin (nutation) when thrown through the air before it settles in its trajectory path. The high frequency is called fast precession and when it is said to go to sleep with low frequency nose wobble (slow precession) around its trajectory when the angle of a attack decreases which is seen in the more reliable groups with less bumps at the edges of the corkscrew. How far these bulges extend outwards depends on the rifling twist of the barrel and the gyroscopic stability match of the projectile to the twist rate.

For educational purposes I post Harold Vaughns diagrams of varying gyroscopic stability factors so you can see how you can be mislead by group shape if it is mistaken for a bump in the high frequency at say 100 hundred yard testing. That's horse and buggy application these days. Sure its easy for people to approximate 1" equals a minute of angle, but that's all in the accuracy stakes at 100 yards for instance. I hope they re-print Harold Vaughn's book because its a keeper for the library with so much relevant information in it. If you can find it, buy it.

To interpret these diagrams you have to imagine you are looking through the rear along the flight path and watching the motion of the nose of the bullet. The effect of seating into the lands not only reduces in bore yaw but it must reduce the angle of attack by reducing high frequency vibrations.

Peter S is just so right. Repeatably and continual refining of work. For some rifle shooting is part of a social and experimenting experience and its not as we age the ability to win that is important but the best we can be to be competitive and enjoy other people's success as part of a bigger tribe; and while we were young, to be developed. Its fun. At some time we all experience a purple patch and the stories keep getting better with time. We don't have to look overseas because in our own backyard we have the equal of others with Peter S and Dave Mac and I would throw in Mincham and Barry Davies too to mentor others. I would like to think we are going to lose the cultural cringe when we can do it for ourselves in this country as Peter says to verify experiments. We on this site are free to disagree to challenge thinking, but I would hope too it is with respect for others who are still learning even though we have a giggle or two with friendly banter. A thumbs up for those that had a go at the questions. They were a sample from a development program which we use on the range. If we have not made mistakes we have never learnt a thing. Yes Sungazer, it's far easier to demonstrate concepts on the spot on the range than to write about it because it is very complex for many if its not watered down and time consuming. It is really step by step over a long time to understand what is going on and then try to master it to repeat the dose. Wise words Peter. Its a lifetime journey this shooting stuff and we must be vigilant to protect our rights to maintain shooting sports in this democracy.


Gyroscopic stability.jpg
You do not have the required permissions to view the files attached to this post.

wsftr
Posts: 52
Joined: Tue Jan 30, 2018 12:58 pm

Re: More on Barrel Tuners

#142 Postby wsftr » Sun Jun 03, 2018 2:48 pm

Williada - thank you for the response (always great responses :) )- yes have read all of B Litz books and T Boyers - pretty much anything I can get my hands on to be honest. Sometimes the same concept gets described different ways. I have to admit after watching the youtube and reading Bryans book/s/articles I had largely discounted a lot of the internet chat and resorted to looking at holes in paper in the complete context i.e. not any one group in particular.
https://www.youtube.com/watch?v=KH9SCbCBHaY
http://www.appliedballisticsllc.com/Art ... Swerve.pdf
So much of what is important comes down to what we consider we need to look for in our targets I think.
There are nuggets in all of those books which I use to some effect as each have a perspective (as you do) on what they look for. The one thing that any new or experienced shooter can take away be they using naked barrels or tuners - start with a method, build on it and refine it. Don't chase the theories haphaphazardly.
I don't believe there is only one way to get "the" load but certainly there are faster or more efficient ways.
My philosophy - theory is the starting point, load dev is the initiation of theory and comps prove or disprove, scores and wins don't prove either way but measured precision does :)
Last edited by wsftr on Sun Jun 03, 2018 5:01 pm, edited 3 times in total.

wsftr
Posts: 52
Joined: Tue Jan 30, 2018 12:58 pm

Re: More on Barrel Tuners

#143 Postby wsftr » Sun Jun 03, 2018 4:54 pm

I thought I would repost Bryans response to positive compensation theory too - it would appear he accepts it.

Note that this 'compensating' effect between MV and barrel harmonics is a known and accepted mechanism for groups to have less vertical at long range than their MV variation would suggest. It's not the answer to the question being asked in the 'Shoot thru Target Challenge', because there we're looking for groups to shrink in MOA in all directions, not just vertical.

williada
Posts: 712
Joined: Wed Jul 22, 2009 12:37 am

Re: More on Barrel Tuners

#144 Postby williada » Sun Jun 03, 2018 9:49 pm

Time to sign out wsftr. Hope this gives you a starting point for test distance question. It refers to Brian's work which I have adapted for you. Cooper also did an excellent one around 2004.

Epicyclic swerve side view.jpg
You do not have the required permissions to view the files attached to this post.

wsftr
Posts: 52
Joined: Tue Jan 30, 2018 12:58 pm

Re: More on Barrel Tuners

#145 Postby wsftr » Mon Jun 04, 2018 7:16 am

Thanks Williada - great posts and you definitely have my brain ticking over (thanks for the time) - always something to ponder. I have been up to my load dev range this morning to re measure :).

GSells
Posts: 267
Joined: Sun Aug 13, 2017 11:04 pm

Re: More on Barrel Tuners

#146 Postby GSells » Sun Jun 10, 2018 5:57 pm

I think it was WSftr that asked about group shapes and if anyone had some to show , or to that effect?
This is shooter neonadathal speak and please test for yourselves.

Ok I was shaking down my 280 ai fast load . 30” Lilja 3 groove , 1:9 twist .
Well a few weeks ago I got a good friend of mine to run some figures through QuickLOAD to check Obt at 2900 fps and at 2930 fps .

It was predicted that the Obt was bang on at 2930 fps and wasn’t too bad at 2900 fps .
Well today , I Shot a few groups that are hardly representative but show the rythemic groups shapes of barrel timing. The faster of the loads at 2945 fps extreme spread of 10 fps with 3 shots in a few fps of each other . Show the bullet beating the harmonics a little too fast but still would be pretty good .

Take .3 of a gr and at 2925 fps the group shape moved to the right at what I look for in a mid to long group of 1-7 o’clock with a es of 14 fps . I believe this is a little better Obt but maybe at the expense of ocw . Both loads I believe would do ok at the longs. But only theory until proven! In the past the
1-7 o’clock groups at 100 yds ( I know I should do it at 140 yds , but don’t have the room !) have been ok at the longs with good water line .

This sort of shows a little with rythemic groups and barrel timing ( I hope !) . There was no weighing of primers , the loads were taken straight of the charge master. So I would expect to see possibly even better results in es and sd with better made ammo !
It’s unfortunate that I’m having a break ( good for my family though !) . As it would have been good to put these loads under Queens conditions!
Even if I do happen to make QLD Queens this year , I’m that rusty ( as I haven’t competed in any Opm’s or serious comps) that if the scores are bad , it will most likely be the nut behind the butt!
But watch this space on the 280 ai ! Big statement, but I believe it’s just as good as a Saum ! :D
Please note the pics have to rotate 90 deg .
You do not have the required permissions to view the files attached to this post.

williada
Posts: 712
Joined: Wed Jul 22, 2009 12:37 am

Re: More on Barrel Tuners

#147 Postby williada » Mon Jun 18, 2018 7:51 pm

Thought I would peruse Benchrest Central and read a comment Gene Beggs posted who I really respect. Think the boys stateside are playing catch up with us in Oz. I notice the phrase "positive compensation" is creeping into their vocabulary. I think Gene's comments are worth a read.

http://benchrest.com/showthread.php?990 ... smart-guys

wsftr
Posts: 52
Joined: Tue Jan 30, 2018 12:58 pm

Re: More on Barrel Tuners

#148 Postby wsftr » Mon Jun 18, 2018 8:25 pm

mmm - its interesting because its loooong been stated that ES doesn't matter SR BR. I assume thats why tuners are a mixed bag in SR BR as really they are a mechanism for tuning on the day which can be achieved other ways. Are high and low powder charges the powder method of positive compensation? - this is what TB looks for and adjusts during the day.

IMO The day I see an F-classer picking a tuner setting for each distance (and it hammering at each distance) will be the day I reckon we will have moved past them being anything more than a dampener.


Return to “Equipment & Technical”

Who is online

Users browsing this forum: ajvanwyk, Taz11 and 7 guests