Tuners For Large Frame Rifles

[otnot]

I recently bought a JP LRI in 6.5 CM. I did all the load development I could but due to the limitations of the magazine of the seating depth I had to stop at 2.814 OAL. It shot consistent .75 MOA groups but I knew it could do better. I really didn't like the 4 lb factory trigger pull so I replaced it with a Triggertech Diamond and set it down to 1.5 lbs. The groups got tighter but still not what I thought they should be. (I know the AR platform is more difficult to shoot)

So one day I happened to see a video of Eric Cortina tuning an AR10 with one of his EC tuner/breaks and thought to myself what the hell it might be what the Dr. ordered so I bought one. I really had my doubts, but after one tuning session I was impressed with the results. This is a picture of the tune: The top row was a quick powder charge test to see what the new tuner liked for a charge. Then I started at a 0 setting and increments of 2 I went to 12. As you can see it settled in at 6-8 and then started to open back up after that. I settled on 7. I think a tuner is a good addition to the AR platform.

 

[hlee]

Now, go back and redo the test and see if you get the same results... Not saying they don't work, but there is not enough data for a statistically relevant assessment in the test presented above.

 

[otnot]

Well sir from my experience it’s damn near impossible to replicate test results due to all the variables involved. I can say this from other tests (different charges) that it tuned very similar to the above test just at different settings.

 

[kthomas]

Now, go back and redo the test and see if you get the same results... Not saying they don't work, but there is not enough data for a statistically relevant assessment in the test presented above.

And as a control, shoot the same amount of groups without a tuner.

I bet from a performance and statistics perspective that not much changes.

 

[hlee]

Well sir from my experience it’s damn near impossible to replicate test results due to all the variables involved. I can say this from other tests (different charges) that it tuned very similar to the above test just at different settings.

If it is not reproducible, is it valid?

 

[bfoosh006]

Interesting .

I have a BAR Mark II with the BOSS system, the BOSS system certainly does effect the precision of the numerous factory loads tried in that BAR.

It took a while for me to figure out the "sweet" spot for the various elk hunting loads I used, but it did shrink group sizes when dailed in correctly.

For that matter, when dailed in wrong, I could readily increase group sizes.

For a hunting rifle, it kinda turned into a PITA... trying different loads required retuning.

Lol, at the time, I think I fired more ammo tuning it than I did fire at Elk.

This was used years ago, so long ago I had a Shepard Scope on it, The Shepard Scope was one of the first Range finding scopes I had ever seen.

For a long distance precision rifle... that has a specific load used routinely, I'd give something like this a try again.

Thanks for sharing.

 

[kthomas]

If it is not reproducible, is it valid?

That's kind of the crux of it.

There's so much statistical variance in our groups, that it's easy to fool ourselves with one small group - especially if it's two or three shots. Open up the sample size and all of a sudden that sweet looking group just appears to be an outlier that may be hard to repeat.

I learned this the hard way doing a bunch of testing with the original RDF bullets. Then with the "Satterlee method" of reloading. And again when the tuner craze hit our disciplines, and I got my hands on a prototype tuner/brake model and did a bunch of testing with it.

As shooters, we assign way to much value to small data sets that are statistically insignificant.

Take that "optimal" tuner setting, and shoot a 5x5 with it. Take the tuner off, and shoot a 5x5. Do this over a few days and various conditions. I bet the tuner starts appearing a lot less relevant.

 

[strikeeagle1]

Byran Litz has a nice treatment of Understanding Dispersion in his Applied Ballistics for Long-Range Shooting, Vol 2.

 

[hlee]

That's kind of the crux of it.

There's so much statistical variance in our groups, that it's easy to fool ourselves with one small group - especially if it's two or three shots. Open up the sample size and all of a sudden that sweet looking group just appears to be an outlier that may be hard to repeat.

I learned this the hard way doing a bunch of testing with the original RDF bullets. Then with the "Satterlee method" of reloading. And again when the tuner craze hit our disciplines, and I got my hands on a prototype tuner/brake model and did a bunch of testing with it.

As shooters, we assign way to much value to small data sets that are statistically insignificant.

Take that "optimal" tuner setting, and shoot a 5x5 with it. Take the tuner off, and shoot a 5x5. Do this over a few days and various conditions. I bet the tuner starts appearing a lot less relevant.

In the pursuit of transparency, I have a Kinetic Security Solutions tuner on a 224 predator that wasn't shooting like I wanted it to. It shoots better with the tuner on it than it does with it off. But, the best setting that I found- in my testing- was the starting point. Luck? Lack of statistical relevance? I don't know, but it shoots smaller groups at 100 yards with the tuner than without, and at the first setting that I tried...

 

[hlee]

Byran Litz has a nice treatment of Understanding Dispersion in his Applied Ballistics for Long-Range Shooting, Vol 2.

Jeez, you're going to owe AB and Brian Litz royalties on that post...

 

[strikeeagle1]

Jeez, you're going to owe AB and Brian Litz royalties on that post...

I am pretty sure that the above single-use reproduction of limited content for the purpose of commentary is protected by the U.S. Copyright Fair Use doctrine and further explained in its U.S. Copyright Office Circular #21.

 

[bigjake83]

I was going to buy one of these and try it out as well with one my Proof 6.5CM Large Frame AR's, I felt with the notable difference in Barrel harmonics with SS Vs Carbon Fiber would be a fun experiment.

 

[kthomas]

I was going to buy one of these and try it out as well with one my Proof 6.5CM Large Frame AR's, I felt with the notable difference in Barrel harmonics with SS Vs Carbon Fiber would be a fun experiment.

Certainly worth trying if you want to experiment.

Report back with your results.

 

[FALex]

Byran Litz has a nice treatment of Understanding Dispersion in his Applied Ballistics for Long-Range Shooting, Vol 2.

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Thank you for posting that, very interesting. These are all topics I have pondered over the years, but have never fully completed the thought into something linearly applied as it was placed on those pages.

Could I trouble you to DM me a couple pics of the page or two following your last pic (under the sub-heading, "Benchrest, or group shooting...")? If it's too much of a PITA, no worries, just wanted to see Bryan's discussion on that.