AusVarmint

How do you set a tunner on a 22rf ?
Once you find a batch of ammo with consistant velosity(as per Tony Z's instructions), what next? Is it mostly vertical we can reduce or does it depend on the rifle?
Thanks in advance
Glenn

Assuming you have a tuner with a range of half an inch adjustment and can be incremented in something fine like a thou at a time when it gets down to the nitty gritty.

Place lots of aiming dots on a card and then place that card at a 100 yards. Pick a good day to do this and make sure you have wind flags.
Now take the tuner off and zero the rifle. Shoot some groups to set some sort of benchmark to better, other wise you are wasting your time, or the tuner is the wrong weight if those groups cannot be CONSISTENTLY bettered.
Fit the tuner and set it to zero zero. Fire two shots at one of the dots at this setting, then turn the tuner to 20 thou and fire another 2 shots, then to 40 thou and fire another 2 shots. Then to 60, 80 and then finally a 100 thou have 2 shots fired for each setting at the same aiming dot. So you end up with one aiming dot that has had ten shots fired at it while adjusting the tuner though a range of a hundred thou. Move onto the next dot and turn the tuner to the 120 thou position and fire 2 shots and then keep repeating as you did previously till you end up with the full range of the tuner having two shots fired on at the tuner settings running through another 100 thou (the first aiming dot will actually have 12 shots on it as you started at zero zero, not at 20 thou).
Now you have five aiming dots, or more if your tuner has a larger range, all with 10 shots fired at them. Look at the ranges and in particular look at the vertical dispersion. Choose the best 100 thou range(s) that show the least vertical. This 100 thou bracket should stand out clearly against the others. If there happen to be two or even three ranges of a 100 thou that show promise, choose the one that is closest to the zero of the rifle when the tuner is removed. The reason for this is too long to describe, but i have found it to be right in every instance i have been associated with. But hey, if it falls in a heap, by all means go and revisit the other 100 thou bracket.

Let's say the best range is 320 to 400 thou. On a new line of aiming dots shoot 2 shots at 320, then 322, 324, 326, 328 and 330. Another aiming dot and then shoot 2 shots at 332, 334, 336, 338 and finally 340. Then so on till you reach the 400 mark. Inspect again for vertical and make the choice of the best ten thou range within that 100 thou bracket. Now let's say it was 392 to 400, as it has been with my tuners in a number of rifles.

On another line of aiming dots fire TEN shots at the 392 setting on a single dot, then ten shots at the 393 setting on another dot, then so forth till you reach 400. There will be one setting that clearly stands out. It may be a little wider than some in that it may not alter the group size through say 394 to 396 as it did in my tuners. But one area will stand out. With my tuners this was a little easier to find than with some others as when you started to get very close to the "tune" the rifle would start to crack. I mean it was so loud that hearing protection had to be worn. This phenomena is not unusual as many in the US have reported this same trait and has been explained by some as akin to that of a tune like in extractors of an engine. In my last rifle it was so loud that it sounded like a 22 Mag going off and it really pissed off those around during matches. But for the 2 years i owned that rifle it never shot under a 490 in Hunter with a high of 496 and all that with jelly beans straight from the tin.

I find it best to shoot all these tests over a chrono. No need to keep check on an average, but just to keep track of a high or low spike that can spoil the test. A low or high velocity shot can and usually will appear with the very best ammo, especially with the number of shots you are about to fire in this session, so you need to take note of where it went and if it really opened up the group. Note it and re shoot that shot.

Now, if you have shot the initial part of this test and you get five or more groups that all look roughly the same, the weight is wrong. It must be weighted until the ranges in the 100 thou stage alter, and alter dramatically in some instances. Now you are probably wondering why i say a 100 yards and not 50 meters or 50 yards? Well, that is easy. The tuner will have an effect on rimfire ammo predominantly in the vertical plain. It cannot alter the pressure time curve and it will never compensate for ammo that is more than 25 fps ES. The reason that it makes way more sense to do it at a 100 yards is that a small movement is accentuated at that range. The other thing is, and this will happen, there will be a time where shots cross over, and this is why it pays to take note of what velocities the shots show while shooting over the chrono and where they strike at the target. This is just not possible at 50 yards all the time, especially as you close in on the tuner range and the thing just shoots a single hole at that 50 y/m. If you get it to hole at a 100 yards, it will always be better at 50, well actually a bit more on that later.

You will often hear it said that there are multiple ranges that work on a tuner. That is wrong and indicates two things. One is that the tuner could be weighted wrong, too heavy or too light, and the other is that the rifle will most likely be shooting to the potential of the ammo and that the tuner is not tuning, but is damping a flyer or spike in frequency. This is exactly how the the Sims vibration slip over dampers work as they do for bows for which this company initially started out in. There is only one frequency, or very narrow range of frequency, that will work. Anything else is just luck and will alter from day to day, temperature to temperature and like many rifles fitted with tuners, show patches of brilliance, and inconsistency.


I said that if it is great at a 100, it will be better at 50. That is not entirely true in my experience. The very tightest grouping at a 100 yards often produced a small vertical slot at fifty yards. So it may need a compromise where it may be just a thou or two of tuner adjustment to round out the 50 yard group if this is what you are mainly shooting like in IRB, RBA etc. My old rifle used 396 for 50 yards/meters and 394 for a 100 yards.

Now the logical question is that once this tuner setting is found, will it be the same for all ammo that is of good nature? Well my experience says yes and no. It shoots well, well enough to be competitive, but i have always found that it could be tuned out better. This is entirely dependent on a pressure time curve and not a velocity. By that i mean that if your Black Match is doing 1060 fps and is tight at both ranges and then you use Lapua Midas and get the same velocity across the chrono, the similarity in velocity does not guarantee that the ammo will perform the same. I found it to be close, but could always be bettered. Different velocities of 25 fps or more had little chance of impacting in the same place or grouping to the same potential. If a velocity spread of this extreme amount of 25 fps was evident in the ammo chosen, a tuner will have it shoot vertical slots at both ranges where that vertical can never be entirely tuned out, but sometimes due to pure randomness may shoot groups that are tight and round.

Trying to apply this method of setting a tuner, and this is nothing more than a simple bracketing method, to a centerfire application, then best of luck. It will no doubt end in a worn out barrel before the tune is found. If you wish to tune out a centerfire, use the thread for the tuner to tension the barrel with a stretcher tube. Works every time.

I do my tuning at 50,you will need 25 aiming points to do the following and I agree with Tony that if you can not find a sweet spot then the weight or lack there off is most likely the cause.

1. Set you tuner to "0" and fire two shots.
Turn tuner one complete revolution (25 clicks) and fire two shots, continue this until you reach "100". You now have a 10 shot group, all shot at the same POA.
2. Repeat step one from "100" to "200"
3. Repeat Step one from "200" to "300".
4. Repeat Step one from "300" to "400"
5. Repeat Step one from "400" to "500". You now have five 10-shot groups.
One of the 10-shot groups will show the smallest vertical stringing. You should have used only 50 rounds so far.

Let's say that you find that the "200" to "300" group shows the least vertical stringing.

6. Starting at "200", shoot 2 five shot groups. Shift to a different POA for each group.
7. Repeat at "225", "250", "275" and "300"
8. One of these settings will show a decrease in group size.

Example: "250" showed the smallest group.

9. Now, start at "245" and shoot a five shot group at 245, 247, 249, 251, 253 and 255.
You will locate the "sweet" spot of your rifle barrel.
10. If you have any doubts, start over at Step #6, and redo the testing.




Regards Chris.

I take it it works the same on a c/f rifle? I have seen a few f class guys using them with success.

G"day All
I just spent 3 hours at the range with my new 1913BR50 and shot of 300 rounds tuning in a lowey tuner.
Im happy to say I used chris's method and my rifle liked the tuner set at 407,It took akmost 2.5 hrs to get it to where I was happy,better than sittin at home though.
The wind gave me a few problems at times but I managaed to wait it out and produce some consistent shooting.
Now to see how it goes on a nice still evening shoot.
Regards
native
PS-dont them tuners get dirty.!!

Thanks for the info guys, looks like I've got a big job ahead of me, I haven't even got the rifle yet and was hoping to shoot it at Leeton this weekend!!!
Thanks again
Glenn

GJS-If you get the gun and find the right ammo and and this is the big one,a DAY with NO wind,you can still do it.
Here today the wind was 5-10klms and switching Left to Right and right to left most of the arvo,be prepared to shoot of a few rounds though.!!
I just love the smell of rimfire projectile lube.!!! .
What sorta rifle you got coming.??
Regards
Native

The wind is forcast to pick up for the weekend and I've got three big days of work booked up.I can shoot under lights but the crony only works under reasonable sun light
I'll post some pics of the rifle later, I wont say what it is just yet 'cause I doubt my shooting will do it justice
Glenn

Interesting thread.

A big thanks to Tony and Chris for taking the time to type out their replies.

regards, curan