Purchased a 3rd Eric Cortina V2 tuner, I've had success with them on my B-14R's so I added one to the BMR.  This carbon BMR favors Lapua Long Range, I've gone through the tuning process and found the setting that works very well and gives great groups at longer distances with the Lapua.  I've been stacking CCI standard velocity deep for years and was curious to see if I could improve the groupings with it and thought I'd get some images of the initial results.  The CCI works decently in the BMR but at 100 yards the groups start to fall apart, my hope was the V2 tuner could extend my range with inexpensive ammo; it's already here so why not try?

Started with a completely clean barrel at 50 yards with the tuner flush to the 1/2 x 28 thread adapter and aligned to 0; there are 4 alignment marks on the adapter to use as reference points and as you adjust the tuner it's rotated back across the barrel.  I've found 3 shots will give you enough information on what settings seem to be giving the best groups and from there you can test those settings more completely.  



Identified multiple tuner settings for further testing, and at 50 yards, 1 revolution #5 was giving the best groups; at 100 yards that setting was giving the best groups this BMR has ever shot with CCI standard velocity.



The wind started picking up so stopped testing, I didn't want the wind skewing the results but I was very pleased with the results so far.  The idea behind a tuner is to find the ammo the rifle prefers, then tune.  It's interesting how even with cheaper CCI this tuner was able to tighten up the groups, next calm wind day I'll continue testing at 100 yards and further out and report back. Tuners do add another variable and might not be for everyone, but if you're willing to take the time you can get some decent results.  

I'm unclear...is that group shot at 50 yards, or 100 yards?

If I can make CCI Standard shoot like Lapua Center-X does out of my BMR, I'll buy one of those tuners immediately.

Its worth reading up on Brian Litz's take on sample size and why a lot of tuning, especially for ammo like SV (which is what I shoot almost exclusively) is chasing your tail. You'd need to shoot almost 20 rounds at each tuner setting to get a sense of a statistically significant change in group size. Couple that with how SV made and I don't think it will ever shoot like Lapua. Litz has said a lot of times that shooters are reading things into 3 and even 5 round groups that don't mean what we think.

@AT-ST83

The first image is of the test of the different tuner settings in 5 position adjustments and was shot at 50 yards, second image was at 100 testing the better tuner results.

@Middlelength

I can't disagree, CCI SV is never going to shoot with the consistency the Lapua does, my hope is to see what a tuner can do to improve it.  What I'm looking for is to minimize the horizontal shift, the tuner can't correct the vertical stringing created by the velocity differences in the SV ammo, only better quality ammo can do that.  At 100 yards the inconsistent nature of the CCI does show and one good group isn't conclusive that a specific setting is the correct one but with enough testing I hope to find enough consistency to fine tune to get the best results the CCI can give.  And it's a great excuse to do a bunch of shooting.  

As far as the tuner itself, this new design using a spring instead of tension screws is reliable in its repeatability, moving the setting off and then back does restore the tune and the quality of the adapters and the tuners is fantastic.  This BMR was silly accurate using Lapua before the tuner, the tuner improved it even more.

I'll look into Brian Litz's writing, you can never have too much information and insight.

Let me preface this by saying I understand how enjoyable testing things can be in the quest for better accuracy.  Also, I appreciate everything you did making these posts.




This does not make sense to me, please explain, if you will.

Unless you shoot indoors, the biggest issue with point of impact is lateral dispersion caused by the wind.  A tuner cannot help you with that.  You even said you quit testing when the wind picked up, showing how important that effect is.

I'm not sure about the velocity variations, either.  I believe people who buy into tuners believe they reduce vertical dispersion.  Your photo appears to show changes in vertical dispersion for different tuner settings and you are using that, in part, to select the preferred tuner setting.

Finally, if you can reduce the overall dispersion using the tuner, that effect could as easily be applied to the Lapua ammo as it could to the CCI.


One thing many people do not seem to understand and apply in their testing and in their thinking is how errors combine.  I won't get into that right now except to say, when you have a big error source (like wind), it renders everything else irrelevant in terms of accuracy.  Add in some shooter error and...  Does it really matter that your group could be a little smaller, if it is strung across a 2" horizontal band and are well off the mark?

I also support the use of larger sample sizes before reaching any conclusion at all.  3 shots just isn't enough to say anything about anything.  


ETA - My questions and comments come from my experiences shooting outdoors using a sling from the prone position at 100 and 200 yards.  I also believe that wind and shooter errors dominate all other error sources rendering things like this irrelevant.  That's where my thinking is at in this point.  I could be wrong.

Partly motivated by this thread, I just ran a bunch of SV through my Tikka T1X across my Magnetospeed. I think I had a total of around 80 FPS in Extreme Spread with a SD or around 30, across maybe 10 rounds. I had velocities from 1010 - 1090. Possibly I was having reading errors as I needed to crank the Magneto to the highest sensitivity setting. FWIW, I shoot almost exclusively SV, and suppressed, because its the cheapest available ammo I can consistently find that is both reasonably accurate and subsonic. I was able to get hits out to about 285 yards on 10" steel. With a 25 yard zero, I was at about 14 mils in elevation to hit at that distance. But I was only connecting 40% of the time. This is all with very little wind.

How would one ever separate the effects of variable muzzle velocities, wind, shooter effects and tuner effects?  That is, once all those are all comparable in size so each could potentially be observed in a test.  

Does the answer to that (if there is one) help Dark Star plan his next test?

Experimented with some different settings at 50 yards using 10 shot groups.  Settings 5 through 10 are showing some promise; there's another node area at 2 revolutions 5 through 30 I'll check next.  This isn't nearly as easy as it was with the Lapua ammo, those sweet spots were much more obvious, with the CCI SV the groups are more chaotic but that was the idea here, can I find a sweet spot to give the best accuracy potential with the SV.  As has been pointed out, there are multiple variables at play with rifle/tuner/ammo/shooter/weather so using larger sample sizes is going to give, hopefully, a better idea of what tuner settings are going to work best for SV.

As always, the fun is in the doing.  

Absolutely.   I was scanning that target set and saw some ok sub series of groups but they are so few shots it isn’t reliable.  Then look at the groups from 2.0 up and then you wonder is that low shot breaking the streak simply a low velocity cartridge.

One can end up chasing your tail.

There's a lot of truth in that post, Rob01.
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..

Doing, or not doing, something just because some "expert" said so is generally not the way to go.  I find testing to be fun.  

There does come a point where the testing ends and you have to just start shooting.  Sometimes the testing just sets your expectations for when you do go shooting.



For reference, I don't have a tuner.  I use mid-priced ammo (Wolf Match Extra).  I use an Anschutz barreled action in an AN-1 tube gun stock.  I am the accuracy-limiting factor - the rounds go exactly where I put them (good or bad).

The EC Tuner works great on my Vudoo 360 with CCI SV.  I'm not interested in arguing about it on the internet though.  I'm not selling tuners so if you don't want one, don't buy one.

I don't think anyone is arguing here.  If you like your tuner, that's great.

These two videos were posted on the ARFCOM Reloading Forum.  They are about the statistical significance of test data (group sizes).

The statistics are 100% applicable here, as well.

More 10 shot groups.  I'm going to start fine tuning in increments of 1 between 2-20 and 2-30.  2-25 is showing promise.

If I make a composite of the three groups fired using 2-5 and a similar composite of the three groups fired using 2-25, I get the same sized group for each 30 round group.  

I just did it visually but a more serious effort could be made to refine the result.

I did this very quickly on a crappy piece of software but you'll get the idea of compsite groups via overlay.

I do not know why this image has been made so small.  Perhaps you can upsize it on your end.  The text is repeated below.



Composite Groups (Overlaid)
Top -  2-5 overlaid on 2-25:  attempting to show how 2-5 compares to 2-25.
Bottom row – 2-5 (left)   2-25 (right):  attempting to show approximately what you'd have if all 30 rounds had been fired onto the same point of aim.


To my eyes, 2-5 and 2-25 are almost identical.  I would suggest you do something similar to the other groups/settings.

It isn't wholly that tuner's don't work - they clearly do work in some disciplines and for some uses. It is just that plenty of people are making tuner conclusions using 3 or 5 round groups and Litz has explained that his testing using larger group sizes for various clients seems to show that 3-5 round groups are really a subset of a 20 (or even better) 50 round shot dispersion. So for example, in this thread, trying to tune for CCI SV, which has a massive ES in velocity, is probably pretty futile. I can see the value in testing a tuner for higher quality ammo where you have less variables at play. But once you have found a "tune" does a 20 round group look different than a 20 round group without the tuner?

Tuners are the new "it" craze and most people can't explain how they even function. Benchrest should settle the Tuner story pretty definitively soon. Scores either fall or they don't...

Good points from trollslayer

I grew up an old school position shooter (3&4P smallbore, service rifle) and I will say ammo and testing it is obviously very important, but I am undoubtedly the biggest limiting factor in my gun performance.

I use a Kidd 10/22 for my precision shooting, and almost everyone on forums will chime in that a semi simply can’t provide the long range accuracy a bolt can.
While that is also undoubtedly true, statistically speaking I account for any misses a whole lot more than the choice in my action type does.
Adjusting for conditions, reading wind and building solid positions on props are all skills I simply have not mastered, (even with decades of competition experience) and these things account for the vast majority of my misses not any equipment limitations.

In comparison we have a very skilled female shooter in our group that uses a Kidd and she easily outshoots me all the time ( ok I may have beat her once) and she usually beats all the bolt gun people except one or two at every match.

People have a hard time admitting when it is them not the equipment- I clearly see and accept it.

I did some more work on Darkstar's group sizes.  This time with a different tool and a little bit more care so I could quantify a few things but it was still very rushed.

I will just post the results with images to come if Darkstar is interested at all.

The composite of the three 10 shot groups for setting 2-5 measures 1.7" wide X 2.5" high.
The composite of the three 10 shot groups for setting 2-25 measures 1.6" wide X 1.6" high.

So, indeed, Darkstar's 2-25 is indeed smaller than 2-5.

As an inveterate "numbers junky", I can offer to look at more significant metrics such as mean radius instead of just a "box" that fits over all the rounds.

The reason to pusue the numbers is to avoid having "to shoot 9,000 rounds".  I'd say, let's get everything we can for the rounds already fired.  Darkstar has done a lot of shooting already.

I have apparently ruffled Ron01's feathers and perhaps the OP's.  Sometimes, what is offered as help is not viewed as such by the recipient.  

I will bow out of this thread unless Darkstar requests something further.

3/4 of ammo and reloading discussions revolve around folks blaming equipment. "Fliers" is one of my favorite shooterisms. If you learn to own every round, your groups suddenly are a lot more predictable.

Tuners have indeed been around for decades
Old rimfire benchrest rifle builder Bill Calfee explains tuners in his book published over a decade ago
https://www.amazon.com/Art-Rimfire-Accuracy-Bill-Calfee/dp/145679776X

More fooling around with the tuner and CCI SV today, 10 round groups at 50 yards.  The 25 setting has been showing the most promise, so I ran the tuner at 2-25, 1-25, and 25.  I know I broke those rando rounds that ended up outside the group clean, but, there they are.  The orange target dots are 3/4 inch.  Right now I'm going to leave the tuner set to 25 and run a few hundred rounds of SV before I consider try a different setting.

What ARCA rail are you using? I'm looking to add one to my BMR.

About 20 years ago I met a very strange guy that shot 22lr matches. He had a tuner on his gun and only shot cci sv. But he did not just shoot it from the box. He bought 10k at a time and measured the rim thickness and weight. He grouped the ammo in to 9 groups in a tik tack toe pattern by weight and rim thickness. Yes he weighed and measured every round. He said he was able to get the same level of accuracy as eley by doing it, but he did have to tune to each ammo group. He would shoot each group until it was gone then move on to the next.

I watched him shoot many sub 1/4" groups that day at 100 yards, he normally shot 200 yard matches. It was also the first time I found out they shot 22lr at 200 yards in matches.

This story is kinda awesome. I wonder how much time he had in that? Takes a specific blend of being: retired, slightly rain-man, frugal, and non-lazy.

10,000 sounds like a lot, however, that's only 1,100 rounds per bin (on average).  That's only two bricks per bin, plus a few (11) rounds to do the tuning.  Almost certainly most of those bins contain an even smaller quantity than that.

Oh well, it's a hobby.  

I don't think I could shoot 1/4" groups at 100 yards, no matter the ammo.

I would assume it was not an even spread, I would figure the center would have say half the rounds, with the rest spread around. Basically culling all the out of spec ones, and use them for practice. But Yes I thought it was a little crazy.

Now I will also say I shout SV almost exclusively and I was at the range one day and a guy had ruger rpr 22 and was trying to find an ammo it liked. I suggested SV and had some with me. The funny part was I had 2 groups at 100 yards that where both about a 1/2 but about an inch apart. I could almost call which which group the bullet would go in to just by sound and feel. I think its good ammo but the qc just allows a wide variation in spec, but not as bad as say something like rem golden.

I have also heard that cci SV is just their match ammo that is found to be out of spec during GC. I would almost believe it.

I'm not sure if I'm going to be weighing rounds and measuring rim thickness, but the CCI SV, the Cortina V2 tuner, and this BMR are working out rather well.  Did some fine tuning and have found the 23 setting was the optimal position using the SV ammo with this carbon fiber barrel.  I've also tested changing the tuner settings and returning it to the 23 setting and it does restore the groups, nice to see the V2 settings are repeatable.

Last Sunday morning's range outing, 10 round groups, 50 yards.



I'm going to replace the stock on the BMR next to get a more vertical grip.