Load tune vs barrel tune

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BATattack
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Load tune vs barrel tune

#1 Postby BATattack » Sun Oct 16, 2016 7:38 pm

What I mean by load tune vs barrel tune is how many of you are tuning for accuracy with little or no regard for ES and purely looking for accuracy and who of you are tuning your loads for low ES and maybe adjusting barrel tuner later??

I have been messing around with a couple of new barrels lately while doing load development and looking at accuracy vs ES at "long" range (800yds). I have also been changing loading techniques looking to learn other aspects which may have a positive or negative effect on accuracy with the intention to apply some lessons learnt on barrels with tuners.

One barrel seems OK .. . . Not as good as others but competitive. The other is just "interesting" and I haven't decided if it's good or bad interesting yet! Haha

I haven't done a huge sample of testing but With this barrel but it seems to have some strange trends with ES vs group size at 800.

Using varying loads 15-20 ES gives around 90mm, 20-25 gives around 65mm and I had on if my last groups give 29mm and a 41 ES!! Neither of these two barrels have tuners YET and I was only panning on installing them on the next two on the way.

So gurus to me at this stage its seeming like at 800yds barrel tune still seems to be more dominant than ES with high BC bullets. . . . . .I haven't had a chance to really play with this at 1000 so it may all turn to custard but looking at the 800yd results this barrel is doing everything it shouldn't! Haha

Brad Y
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Re: Load tune vs barrel tune

#2 Postby Brad Y » Sun Oct 16, 2016 11:24 pm

I wondered about this today. FWIW and while I take note of the numbers, I tune a load to the barrel first then introduce tuners later. If that all relates with good numbers then all sweet. If not and it still holds flat elevation relative to the conditions then the numbers don't worry me too much. A few 1000yd BR shooters in the USA that I talk to often don't put all that much emphasis on finding single digit numbers- especially on larger capacity cases. While other members on here have shared info on what certain spreads gave give in vertical dispersion at long range, most have been quick to add that barrels will be barrels and sometimes tight grouping and low numbers often won't coexist and that the target will tell the story.

KHGS
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Re: Load tune vs barrel tune

#3 Postby KHGS » Mon Oct 17, 2016 7:50 am

Brad Y wrote:I wondered about this today. FWIW and while I take note of the numbers, I tune a load to the barrel first then introduce tuners later. If that all relates with good numbers then all sweet. If not and it still holds flat elevation relative to the conditions then the numbers don't worry me too much. A few 1000yd BR shooters in the USA that I talk to often don't put all that much emphasis on finding single digit numbers- especially on larger capacity cases. While other members on here have shared info on what certain spreads gave give in vertical dispersion at long range, most have been quick to add that barrels will be barrels and sometimes tight grouping and low numbers often won't coexist and that the target will tell the story.


So very TRUE! I have said time & time again, good figures are a GUIDE only. Shape of the group & consistency are what determines a good barrel & accurate load.
Keith H. :)

Send-it
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Re: Load tune vs barrel tune

#4 Postby Send-it » Mon Oct 17, 2016 4:04 pm

i just load for accuracy.
i couldn't care what the speeds are.
if its accurate and holds great elevation at short, medium and long distances then that'll do.
i wouldn't properly know what the true muzzle velocity is, apart from punching the trajectories into a worthy ballistics program.

johnk
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Re: Load tune vs barrel tune

#5 Postby johnk » Mon Oct 17, 2016 5:18 pm

I've always loaded my Match Rifles for spread at acceptable velocities , then used a KHGS tuner or the like to tame the group.

Works for me in that environment.

plumbs7
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Re: Load tune vs barrel tune

#6 Postby plumbs7 » Mon Oct 17, 2016 6:33 pm

At the end of the Day the target tells the story! It's near impossible or is quite difficult to get a rifle to shoot the x ring out at 300 yds and then be competitive or an x ring cutter at 1000 yds ! That's in my opinion with a naked rifle barrel!
Image
"Barrel vibration is one of the largest contributors to rifle accuracy" Harold Vaughn.
My testing seems to support the above statement! ( insert form Bryan Litz's book)
Willaida's system of round Robbin grouping and positive compensation has helped a lot of shooters up here Qld and in Wa and is a very scientific and fool proof way of tuning a rifle , especially a naked rifle (no dampener or tuner) . Davids method is trying to get the mode 1 vibrations and thus launch angles in sync to also extend the node also fool proofing for a greater extreme spread !

That's great but what happens when the weather goes cold or the barrel speeds up or slows down due wearing in or out or throat erosion and seat depth! ??
Good chance you may even get negative compensation with large vertical. This also can be sideways as well.
Optimum charge weight is tying in barrel harmonics / timing and tying it in with extreme spread and sd's.
Of late we've been told that to hold x ring elevation at 1000 yds you have be at least in single figures for sd with a 7 mm and lobbing in .308 , 200 gr the problem is exponential and that more difficult!
In conclusion for harmonics, if you don't have an understanding and harmonics under control in load development, one maybe chasing their tail! I'm a big fan of dampeners that just " keep it simple stupid " Cam and Julie's rifles were tuned the same way and beat the world with ballistically inferior speed but superior accuracy ( and great wind coaches :wink: ).
I'm so greatfull for the few years I spent with him as it shapes some of my views on things! But I asked him once whether he used his dasher ( Queens level ) at the shorts and then switched over to the shehane athe mids and longs?
His reply to me was " I have them that well tuned that we just shoot them all the way through! I believe that was at Wandai Opm where he didn't drop a shot on that second day ( the only day that they competed )! Photo courtesy of D Aarons
Image
This was Cam's last prize meet ! Northarm where shot the centre out at 300ms with a 60.9 with his Saum ! He understood harmonics!
So what do I do? Well I'm most likely not very qualified to comment! I'll go with Brad and say Fwiw!
Low sd and group shape is very important ! The group shape of my .284 at 100 ms was not overly impressive but had a low sd . But at 600 yds in testing was capable of punching hole on hole at 600 yds and was quite impressive at the ton At squad ( wild dog Smithed Brux well we think it's a brux! Not sure). Like I always say , I could be full of poo poo! The target tells the story! :lol:

RDavies
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Re: Load tune vs barrel tune

#7 Postby RDavies » Mon Oct 17, 2016 9:00 pm

BATattack wrote:What I mean by load tune vs barrel tune is how many of you are tuning for accuracy with little or no regard for ES and purely looking for accuracy and who of you are tuning your loads for low ES and maybe adjusting barrel tuner later??

I have been messing around with a couple of new barrels lately while doing load development and looking at accuracy vs ES at "long" range (800yds). I have also been changing loading techniques looking to learn other aspects which may have a positive or negative effect on accuracy with the intention to apply some lessons learnt on barrels with tuners.

One barrel seems OK .. . . Not as good as others but competitive. The other is just "interesting" and I haven't decided if it's good or bad interesting yet! Haha

I haven't done a huge sample of testing but With this barrel but it seems to have some strange trends with ES vs group size at 800.

Using varying loads 15-20 ES gives around 90mm, 20-25 gives around 65mm and I had on if my last groups give 29mm and a 41 ES!! Neither of these two barrels have tuners YET and I was only panning on installing them on the next two on the way.

So gurus to me at this stage its seeming like at 800yds barrel tune still seems to be more dominant than ES with high BC bullets. . . . . .I haven't had a chance to really play with this at 1000 so it may all turn to custard but looking at the 800yd results this barrel is doing everything it shouldn't! Haha

I'm certainly no ballistics guru but what you have found makes perfect sense and is pretty common. There are SO many good rifles out there out to 800yds and maybe no too bad at 900, but how many rifles out there will hold reasonable accuracy at 1000 when tune AND low ES/SD becomes important? What you have found with regard to accuracy getting worse as ES/SD gets better is also very explainable if the load tune does not match up with the barrel tune. For instance, I have seen a few barrels come into tune at say 2950 fps, but their ES/SD came down as the load was bumped up to 3000+ fps (or dropped down to 2900fps). Unfortunately the barrel went out of tune at that speed but luckily their ES/SD was acceptable enough to get by at the barrel node speed.
Now if your barrel is one where the barrel tune does not align with load tune, then a tuner might help to bring them into alignment giving you more CONSISTANT accuracy at 1000yds.

BATattack
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Re: Load tune vs barrel tune

#8 Postby BATattack » Mon Oct 17, 2016 9:45 pm

I have always previously loaded for accuracy with very little or no regard for ES. I've always done my testing at mid to long range and achieved mostly "acceptable" results while continuously looking for ways to improve.

After developing several barrels to what I felt were the best they could be using OCW (I do my testing differently to willanda but essentially looking for similar trends) it leaves me wondering "could they be MORE accurate and is there a BETTER method?"

For me 2 things make that hard to answer through testing. 1 being barrel life of FO calibers often only allows enough testing for one method or a limited number of components while using the same barrel before changing to another barrel which is an unknown variable. 2 being weather conditions at 1000yds . . . . It's not often we get conditions at 800 let alone 1000 that will produce meaningful results.

18 months ago i would have thought that if I had a rifle that shot well at 500 my tune is good and my ES must be good. This testing has shown that barrel tune is still seems to be "dominant" out to at least 800yds and how much further it holds is going to be interesting. I'm not saying I want to be anywhere near 41 ES but as you mentioned Rod I may try a load that is a reasonable balance between ES and tune in the short term.

Ideally I'd like both the barrel and load to be in perfect tune and that will be the next step over the coming months while trying to apply some lessons learnt!

Old Trev-39
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Re: Load tune vs barrel tune

#9 Postby Old Trev-39 » Tue Oct 18, 2016 8:51 pm

I tune my .284 at 100yds. to get small groups. I then add a Purdy calculated tuner to the barrel and go and shoot.This year I have shot 16 groups in the 1000yd. B/R. comp and have an average group size of 8.923. Most of these have been shot on the Townsville range which very seldom sees good conditions. My M/V. is around the 2860 mark with the 175 Sierra M/K. Last time checked E.S.10 S.D.4. This was over an old 2 screen Ohler with screens about 1200mm.apart.
Cheers, Trevor.

BATattack
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Re: Load tune vs barrel tune

#10 Postby BATattack » Fri Oct 21, 2016 5:18 pm

OK bit of an update!

I've had a chance to get back to the range and repeat the testing 1000 and at this range the velocity is definitely starting to have more effect. Loads with 25fps ES would struggle to hold 6 ring while those with around 15fps or better AND good barrel tune were around X ring or better.


Old Trev-39 wrote:I tune my .284 at 100yds. to get small groups. I then add a Purdy calculated tuner to the barrel and go and shoot.This year I have shot 16 groups in the 1000yd. B/R. comp and have an average group size of 8.923. Most of these have been shot on the Townsville range which very seldom sees good conditions. My M/V. is around the 2860 mark with the 175 Sierra M/K. Last time checked E.S.10 S.D.4. This was over an old 2 screen Ohler with screens about 1200mm.apart.
Cheers, Trevor.


Trev that's a pretty impressive agg across 16 targets considering BR is measured across the most extreme shots! My next two barrels will have tuners and although I already have I development plan I'll read up on the Purdy method.

williada
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Re: Load tune vs barrel tune

#11 Postby williada » Fri Oct 21, 2016 6:41 pm

Trev, glad to see that tuner working for you. Are you using the bore ratio for the tuner bloop section I suggested?

Adam, I was going to contribute earlier but it took a while to draw a few diagrams on the computer which are posted below.

There are a lot of things to link together before you use a barrel of the correct harmonic length or a tuner forward of the muzzle to fool the barrel into operating at the correct harmonic length to deal with reflected vibrations and the weight of that tuner if you are considering damping the torque effects as well.

Getting the load development right to match your barrel profile is very important before you add a tuner. Particularly in relation to another thread on choosing the right powder and primer combination. The Purdy values are velocity dependent, so the use of the best powder/primer/ projectile combination must be determined first. The cutback lengths of the bloop section in the tube are tiny for each harmonic value. This is one of the reasons I have nagged about doing load development before adding a tuner for a few years. It is still an art more than a science and several tube lengths have to be tried to find an harmonic length.

Remember stock balance is also very important.

Hope the following makes it easier to grasp some of the concepts.

Image

Old Trev-39
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Re: Load tune vs barrel tune

#12 Postby Old Trev-39 » Fri Oct 21, 2016 7:48 pm

Yes I am using that bore ratio on both .284 (.814) and 6.5 (.757).
In the 1000yd B/R. I am only interested in group size not score as some targets show. As long as all 5 shots are on paper I do not care where they are. It would be nice to have a 50.5 and a 4" group, maybe one day all the stars will align. For those not familiar with 1000yd. B/R. light gun shoot 5shots,heavy gun shoots 10 shots. I shoot in the light gun category.
Cheers,
Trevor.

plumbs7
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Re: Load tune vs barrel tune

#13 Postby plumbs7 » Sat Oct 22, 2016 9:34 am

Ok I've brought this post back over to where it should be ! Read my last post on .284 small primer to make sense.
Ok below is when I was trying to prove the lil 7/08 Ai for teams and pushing 180's way too hard ! So this info is obsolete now and was just before the Nats. The conditions came near perfect except a slight drop off wind from 1-2 o'clock. I had 10 rounds left and wanted some data at 1000 yds.
Image
Shot 1 2801 fps- sighter and the difference between light and dark target about 5/8moa.
2 2796
3 2790
4 2810
5 2804
6 2804 , must have been me or conditions?
7 2808
8 2818
9 2802
10 2810

This tune was brilliant at 300 yds and 800 yds up but always was a little off at 500 and 600 yds . But not renewing cases enough took it toll and the lil cal fell over later on !
Funny thing was , I dropped a grain of the load and at ranges tested so far , 300,500,600 and 700 m's it seemed like I could close my eyes , pull the trigger and it was in the middle or x ring! That is it made me look like a much better shot than I am ! It seem to buck the wind! ( I'll be using the lil 7/08 Ai at Northarm. And Northarm being a #+*#^ of a place may just come last again ! So don't blame the rifle lol!).

Getting back to the chrony plots except shot 6 , that tune was indicating a slight positive tune! ????

KHGS
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Re: Load tune vs barrel tune

#14 Postby KHGS » Sat Oct 22, 2016 10:04 am

[quote="plumbs7"]Ok I've brought this post back over to where it should be ! Read my last post on .284 small primer to make sense.
Ok below is when I was trying to prove the lil 7/08 Ai for teams and pushing 180's way too hard ! So this info is obsolete now and was just before the Nats. The conditions came near perfect except a slight drop off wind from 1-2 o'clock. I had 10 rounds left and wanted some data at 1000 yds.
Image
Shot 1 2801 fps- sighter and the difference between light and dark target about 5/8moa.
2 2796
3 2790
4 2810
5 2804
6 2804 , must have been me or conditions?
7 2808
8 2818
9 2802
10 2810

This tune was brilliant at 300 yds and 800 yds up but always was a little off at 500 and 600 yds . But not renewing cases enough took it toll and the lil cal fell over later on !
Funny thing was , I dropped a grain of the load and at ranges tested so far , 300,500,600 and 700 m's it seemed like I could close my eyes , pull the trigger and it was in the middle or x ring! That is it made me look like a much better shot than I am ! It seem to buck the wind! ( I'll be using the lil 7/08 Ai at Northarm. And Northarm being a #+*#^ of a place may just come last again ! So don't blame the rifle lol!).
I

Getting back to the chrony plots except shot 6 , that tune was indicating a slight positive tune! ????[/quote

Indicates & reinforces what I have been saying for eons, the correct node is never the high one. This high node is always narrower than the correct 3/4 throttle node & ruins your brass & shortens barrel life by up to 30%. Most of the time more consistant accuracy over a wider range of conditions will result from what I call the 3/4 throttle node.
Keith H.

plumbs7
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Re: Load tune vs barrel tune

#15 Postby plumbs7 » Sat Oct 22, 2016 11:44 am

Hi Keith , yes I regret very much ; or should I say that I can be a little pig headed and stubborn at times ( maybe a little arrogant too :D ). As lots of people were saying at squad level to change to .284 win. I think our Se qld captain said it best ,"stop f#^#*king around and get a .284!).

.284 has been a joy to tune as you say Keith in that 3/4 throttle node!
I went the long way round and in denial with the 7-08 and found out the hard way! Thanks for the input as it makes sense! =D>


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