Barrel Tuners (not rimfire)

[Tony Z]

OK, been chatting with El Jacquo on and off for a while now and as things do, the talk gets around to rifle stuff. Reamers, barrels, actions, scopes, and of course, tuners.

Yet another attempt but without the rimfire tuner thought contamination in the process. That will explain itself as i go along.
The usual method, outside of the Rx formula, is pick ammo to try, find the best ammo that prints nice and consistent, then bolt on the tuner and wind away, where hopefully inside the barrels life span, you find a sweet spot. Not such an issue with a rimfire but can be rather taxing on a 7SAUM.
So for a long while we've been chatting, then surfing, then scheming. Then deciding to retrace through the logic and deciding on what is the objective?
Even the most experienced say you find a tune only to need to know how to adjust when atmospherics alter. To me that defeats the purpose as Murphy says you will turn the wrong way at some point.
More recently there are evolving the set once and forget guys like Bukys and Schmidt, and others, that adjust charges during the match, predominantly on DA variations, much like a top fueler in drag racing, and never turn the tuner from lock until the barrel gets tossed.
There is now a third method. Determine the required tuner/damper weight, set once and load once, but fine tune adjust a thou or two tops from the initial set. That is what i have been doing in recent weeks but without the real serious seating depth or primer change tuning. That will come later. This is more about throw it together and see if it has merit.

6BR HV barrel 24 inches long, 1 in 14 twist set in a single shot Deviant RBLPLE action. Barrel was threaded at 32 TPI on the muzzle for 35 mm, a tuner of the calculated weight installed 3 turns from the shoulder and locked solid. Two bullet types shot at jam with various loads of 8208. First outing was a horrible day, but i saw something i have never seen before. Next time out was a better day and i shot again at 200 yards and the same phenomenon of no elevation change was there.

It may not look like much or even anything near a match winner, but the evidence is there in the pic within three groups over a range of a full grain of powder, 32.5, 33 and 33.5 grains of 8208(bottom row) and a bit less powder with the 70 SMKs. That range of powder is good for between a 100 to a 150 fps at this high end of pressure with that cartridge and on a bare barrel you will always see a change in elevation.

It appears the set and forget, tune load as per normal, and settle on that has some merit. The only bit to test is the maximum of just one or two thou turn in or out to really zone in the tune. A multiple US BR match winner says it does and beyond that it is both a waste of time and detrimental to the desired outcome.

It may not seem much, but if you can get the same POI over that range of powder charge and a heating barrel, it means everything, even for this crow gun shot off a bipod. So for the moment, with this test at least, my opinion of tuners on a centerfire are shifting. We'll see at the next outing.

[kickinback]

Will you walk away from stretcher tubes or do you have more to do there?


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[Tony Z]

Tubes are a different animal kickin. They shoot good groups from the moment you put them on but unlike this particular tuner test, the increase in powder charge shows an elevation increase at the target in a very progressive manner. From low to high, not low high low high like with some bare barrels and the usual sine wave. I doubt a tube or a tuner can make a barrel shoot groups better than careful load development can garner, but i do believe both may widen the accuracy node which can reduce the atmospheric effect considerably. As seen in Narromine where the load i tuned here in the north shot very well in reduced humidity and temperature down there.

What is different this time with the tuner this time around is both the weight and the method. The weight was calculated in the 10 to 15% accepted theory of either a long or short barrel so that the dog didn't wag the tail, or the tail didn't wag the dog. A point of neutrality. A short barrel on the higher weight percentage, and a long barrel on the lighter spectrum being further from the receiver having more leverage. The actual weight of tuners has been a point of discussion for a very long time where there are examples of tuners that weigh pounds and others that weigh ounces. Both have an effect, but which remains constant is the real holy grail.

My view is that you can purchase a Bukys or EC or a Schmidt tuner and tune away. Unless you stick it on a 21.75 inch LV/HV barrel you may have issues. A tube has none of that and that is why i will always advocate a tube over a tuner until a valid formula exists, which i believe is close by now.

[Brad Y]

Heres a question Tony, do you believe the key is weight or the benefits the weight offers eg vibration absorbing properties. Therefore could you get away with lighter but with extra vibration absorbing properties to get the same result? Im personally seeing great results with a very light tuner, the same as I would no doubt with a heavier one. The only thing is it takes larger adjustments to have the same effect. Ie if a heavier tuner goes into and out and back into tune in one full revolution, then the lighter one does the same in 2 revolutions. So easy to over complicate on theory instead of focusing on what they are doing- you determine if they work or not by your load testing and replication, replication, replication.

By the way I have sourced a new action that comes with an ex Aus TR team barrel that is supposedly both very new and shoots very well possibly even hummer status (in our sport anyway) I must admit, very tempted to put a tube on it and have a tinker, it might just be the ticket with 155-185's

[Tony Z]

Went out today to fine tune the load a bit. I went with the 33.5 grains of 8208 for no other reason than speed as this is a crow rifle after all even though it has a bloody heavy Nightforce BR scope and tuner. The pill is the same 68 Berger, 205M primers. I altered seating depth from jam point to jammed in 10 thou then jumped 10 and 20 thou. Conditions were favourable being overcast and a gentle breeze switching from left to right. Using the DD reticle was great , just cover the black dot with the dot, wait for the wind to look right and touch the 1/2 ounce Jewell.
The groups are self explanatory. Looks like bullet jump is a no, but i must confess that a tiny portion of the verticle may be somewhat induced by the bipod. There were a number of shots in the latter groups that just didn't seem right in the sight picture during recoil. There is no doubt that a good BR stock and slippery set of bags would improve these groups. But as i said, it's a crow gun.

I will settle on 33.5 grains 8208 and 10 thou jam. Then i will try turning the tuner a thou in and out to see what happens to see if the theory holds. I really don't see any gain as that first group could have been tiny with a good set of wind flags. And yes the wide shot right was the last. Of course.
Of interest is the verical impact. No change in three weeks, a much warmer day and higher humidity and the two foulers went into the center above the orange dot used in the last outing shown with the earlier groups. That is odd, dead cold clean barrel at 200 yards.

Of note is the 20 thou jump group. If anything it is a touch higher than the others where it would, should, be somewhat slower because of the jump, yet it is right there at 200 yards. But as i said, not entirely happy shooting this test off a bipod and i do have a question mark on that high bullet. The group being to the right a bit is just wind which in itself raises a question because the amount of drift i was expecting today is way less than i got. Hummer maybe? Or i just suck at wind estimation.

If i see zip with the tuner adjustment at 200 tomorrow, which i feel is going to be the case, 3 or 400 yards may give a better indication of effect.

[Brad Y]

Try upping the powder a little and re trying the jump. But that is impressive vertical nonetheless.