Differences at 50 & 100 yds.

[Hi-NV Shooter]

Enough speculation from the great unwashed and inarticulate. It is a simple reproducible fact that 2 clicks on a Harrell tuner , on a Suhl 26” barrel, is the difference between the Tune at 50 and 100 yds this setup has Positive Compensation. A 22 with no positive compensation can shoot well but is wholly dependent on low sd/es ammo over a range of temperatures, a sparkle-farting unicorn. Naysayers: kindly refer to Varmint Al’s work. Seymour

If you truly have PC you would not need to adjust 2-clicks to make it shoot better at 100yds. again if truly PC is achieved it will negate any variables in the ammo, that would affect how it shot at 50 & 100 it would only matter on scope adjustment between the distances.

Lee

 

[grauhanen]

If you truly have PC (positive compensation) the tuner setting would theoretically produce one hole results at one distance only. In other words, positive compensation works for a specific distance. If it were not this way, it would require the tuner to cause rounds with different MV's to have the same POI at every distance. The fact that different MV's will occur with every ammo. It's the trajectory at a given distance that's affected by the tuner, not the MV. The tuner can't simultaneously affect both trajectory and MV over an infinite set of distances. Something's got to give.

With regard to results at 100 being better (MOA-wise) than at 50, it does happen, but not very often and not on demand. To see such results, it is necessary to shoot the exact same rounds at both distances. Different rounds from the same lot can't produce sufficiently reliable results. The same rounds must be used to compare results at the two distances.

This is can be done at places like the Lapua testing facility where electronic sensors produce a target simulation at both 50 yards and 100. The flight of the ammo is unaffected as it passes 50 meters and continues to 100. As a result it is possible to compare results at 50 and 100 as apples to apples.

When the 100 meter results are better (MOA-wise) than they are at 50, it's not because the ammo "sobered" up and flew better after passing the mid-way point. Normally, convergence doesn't happen. On those unexpected and unpredictable times that it does, it's because the center of gravity of some rounds affect their flight differently than that of others, with the result that some groups may have better results at 100 than they do at 50 (MOA-wise). This information has been posted elsewhere by Landy(HuskerP7M8), the well known and respected student of .22LR ammo behavior. If I've misrepresented what he's said, I'll apologize in advance and welcome correction.

Usually, .22LR ammo performance is non-linear. That is as distance doubles, group size usually more than doubles. Except for the unpredictable and unanticipated effect of center of gravity inconsistency, groups get larger and larger MOA-wise as distance increases. Landy has posted calculations from his study of Lapua test tunnel results at 50 and 100 meters and says that on average group size increases by a ratio of about 2.14 from 50 to 100 meters. Of course, some will be by more, some by less. Again, if I've misrepresented Landy's work, I apologize in advance and welcome correction.

 

[tovaert]

Perhaps shoot the same bullet through two (inline) targets faces, one at 50 and one at 100, on a dead-calm day, with a dirty barrel/chamber, and then measure the group size in MOA?

 

[wkdickinson]

Check this article out from here on Accurate Shooter a few years ago:

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[redrockranger]

I have not found this to be true. You have something else going on.

WIND........

 

[grauhanen]

Check this article out from here on Accurate Shooter a few years ago:
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No doubt these results have influenced many shooters in trying to select ammo varieties to use. It's worth noting that these tests were done over ten years ago, many of them with ammo varieties no longer available.

Unfortunately, this particular set of tests doesn't give any conclusive information. The tests referred to make no pretense to be comparing the same ammo at different distances. That's what makes the Lapua test facility results unique and worth looking at. In fact, it's unknown whether the results of the same variety of ammo at the different distances were done with the same lot or if different lots were used. This is a key piece of information that's not included.

 

[wkdickinson]

No doubt these results have influenced many shooters in trying to select ammo varieties to use. It's worth noting that these tests were done over ten years ago, many of them with ammo varieties no longer available.

Unfortunately, this particular set of tests doesn't give any conclusive information. The tests referred to make no pretense to be comparing the same ammo at different distances. That's what makes the Lapua test facility results unique and worth looking at. In fact, it's unknown whether the results of the same variety of ammo at the different distances were done with the same lot or if different lots were used. This is a key piece of information that's not included.

I agree, the data developed at the Lapua test facility is far more valid.

 

[biggun2869]

I am fairly new to “long range” .22 shooting. In excess of fifty years ago, I shot competitively indoors. Since becoming sucked into this new discipline, it was suggested that I try several brands of ammunition to find which my rifle ( old Savage Anschutz 164 Sporter ) prefered. I bought six different boxes that were of varying prices. If I remember correctly, the most expensive was Lapua Center X. I also had two old bricks of Winchester T22 leftover from competition days.
We set up at 50 yds. and shot the different brands, Federal, Eley, SK and others which I don’t recall. We then stretched out to 100 and shot again. It seemed to both of us that some of the more expensive ammo grouped nicely at 50. The T22 didn’t print quite as well. When we moved out to 100, the T22 appeared to both of us to group the best of all. I don’t understand why. I thought someone might have experienced a similar situation and could suggest a cause.
The fellow who was shooting with me has suggested that it may have something to do with differing velocities. I have yet to try any .22s through my chronograph. Could this have any bearing on accuracy. I’m stumped. There may be something very simple that I am overlooking.
Here’s another kick in the butt. I purchased a CZ 457 MTR, installed a 24 X scope, Harrell tuner and adjusted the trigger down as far as I am comfortable with. It has yet to outshoot the old Anschutz. There’s much more to this game than appears on the surface.

I have shot a crapload of T22, it was cheap and it shot great. The old old stuff in the white box was swaged and I liked it the best. The newer silver box still shot fine.
This is another reason why 22 ammo is way over priced, also another reason I don't understand why US manufacturers can't make accurate 22s. I don't know how many bricks of T22 I've bought for 10 12 dollars in the 70s. Money was worth a lot more then but not 10-15 times as much

 

[Hi-NV Shooter]

If you truly have PC (positive compensation) the tuner setting would theoretically produce one hole results at one distance only. In other words, positive compensation works for a specific distance. If it were not this way, it would require the tuner to cause rounds with different MV's to have the same POI at every distance. The fact that different MV's will occur with every ammo. It's the trajectory at a given distance that's affected by the tuner, not the MV. The tuner can't simultaneously affect both trajectory and MV over an infinite set of distances. Something's got to give.

With regard to results at 100 being better (MOA-wise) than at 50, it does happen, but not very often and not on demand. To see such results, it is necessary to shoot the exact same rounds at both distances. Different rounds from the same lot can't produce sufficiently reliable results. The same rounds must be used to compare results at the two distances.

This is can be done at places like the Lapua testing facility where electronic sensors produce a target simulation at both 50 yards and 100. The flight of the ammo is unaffected as it passes 50 meters and continues to 100. As a result it is possible to compare results at 50 and 100 as apples to apples.

When the 100 meter results are better (MOA-wise) than they are at 50, it's not because the ammo "sobered" up and flew better after passing the mid-way point. Normally, convergence doesn't happen. On those unexpected and unpredictable times that it does, it's because the center of gravity of some rounds affect their flight differently than that of others, with the result that some groups may have better results at 100 than they do at 50 (MOA-wise). This information has been posted elsewhere by Landy(HuskerP7M8), the well known and respected student of .22LR ammo behavior. If I've misrepresented what he's said, I'll apologize in advance and welcome correction.

Usually, .22LR ammo performance is non-linear. That is as distance doubles, group size usually more than doubles. Except for the unpredictable and unanticipated effect of center of gravity inconsistency, groups get larger and larger MOA-wise as distance increases. Landy has posted calculations from his study of Lapua test tunnel results at 50 and 100 meters and says that on average group size increases by a ratio of about 2.14 from 50 to 100 meters. Of course, some will be by more, some by less. Again, if I've misrepresented Landy's work, I apologize in advance and welcome correction.

Have you seen a rifle that achieved PC? I can say I have never seen one, and may never in my life time.

PC is suppose to compensate for the ammo's variables in MV, so with this said if say a lot has rounds that vary in MV between 20-40 fps it would still place shots same POI right? if the rifle is truly PC
however if you are zeroed at 50yds. how can POA/POI be the same at 100yds. this is what I meant by scope adjustment being the only thing needed if you truly achieved PC.

Another thing is the barrel is it capable to achieve PC? ammo is one thing and the barrel is another. they both need to work together to get the best results.

Lee

 

[grauhanen]

PC is suppose to compensate for the ammo's variables in MV, so with this said if say a lot has rounds that vary in MV between 20-40 fps it would still place shots same POI right? if the rifle is truly PC
however if you are zeroed at 50yds. how can POA/POI be the same at 100yds. this is what I meant by scope adjustment being the only thing needed if you truly achieved PC.

I don't know how a tuner works. Does it do what it does because of what's often called "positive compensation" -- or is it something else?

There's some lack of clarity on what is meant by PC or "positive compensation". Therefore, there is need for agreement on what is meant.

Many shooters understand it as described by Varmint Al (http://www.varmintal.com/a22lr.htm), which I believe is to say that by means of a correctly adjusted tuner a slower round is launched to a higher arc than a faster one and this achieves the same POI at a certain distance.

Is this what is meant by positive compensation? Is the Varmint Al explanation of how tuners do what they do accurate and complete?

If it is, then it follows that the same tuner setting that works to achieve the same POI at one distance wouldn't work at another.

At the same time, if it is correct it also suggests that if one tuner setting works at both 50 and 100 yards, then something else other than the Varmint Al explanation of positive compensation explains what happens and it can't be PC.

Of course, I may be misunderstanding positive compensation altogether. Perhaps the Varmint Al explanation is inaccurate or incomplete or I misunderstand what he's said. I would welcome any further information about how a tuner works.

 

[Hi-NV Shooter]

I don't know how a tuner works. Does it do what it does because of what's often called "positive compensation" -- or is it something else?

There's some lack of clarity on what is meant by PC or "positive compensation". Therefore, there is need for agreement on what is meant.

Many shooters understand it as described by Varmint Al (http://www.varmintal.com/a22lr.htm), which I believe is to say that by means of a correctly adjusted tuner a slower round is launched to a higher arc than a faster one and this achieves the same POI at a certain distance.

Is this what is meant by positive compensation? Is the Varmint Al explanation of how tuners do what they do accurate and complete?

If it is, then it follows that the same tuner setting that works to achieve the same POI at one distance wouldn't work at another.

At the same time, if it is correct it also suggests that if one tuner setting works at both 50 and 100 yards, then something else other than the Varmint Al explanation of positive compensation explains what happens and it can't be PC.

Of course, I may be misunderstanding positive compensation altogether. Perhaps the Varmint Al explanation is inaccurate or incomplete or I misunderstand what he's said. I would welcome any further information about how a tuner works.

From my experience a tuner is used to time the barrel or correctly time the bullet's exit out of the barrel. the barrel moves in a elliptical pattern, the tuner is used to slow or speed up that movement of the barrel by placing weight forward of the crown. however it is placing the exact amount of weight that will yield the best results. when you adjust the tuner it will move in the case of a Harrell 0.001 for each click, even this small amount of movement will change the weight at the crown.
the way I tune is with tuners less than a standard Harrell which weigh 8.0-8.75 oz. I use tuners that weigh from 4.125 oz.-5.5 oz. it depends on the rifle's barrel profile and length.
I also believe once you find the correct setting you do not need to move or make adjustments again, regardless of any condition or distance. Bill Calfee calls it a stopped muzzle, I don't know in my case as I believe the barrel needs to move.
now here is where the theory of PC comes in, as I understand what PC is about, it will have a slower bullet exit at a higher barrel position and a faster bullet exit at a position that will be below the slower bullet's, as we know a bullet will not straight-line, but will follow an arc so in PC, if you have PC, that faster bullet will have the same POI as the slower bullet's POI. the reason the slower bullet which exited at a higher barrel position, combined with the higher barrel position and natural arc of the bullets flight it will have a POI that is higher than the velocity would normally allow. if no compensation was occurring, then the faster bullet will have a higher POI and the slower bullet will have a lower POI all because of the difference in velocity.
So if you take PC as it is suppose to be, any lot of ammo will have the same POI as any other, since PC is suppose to make up the velocity difference or compensate between the lot speeds so they have same POI.

Now for PC saying at different distances the tuner setting will not be the same. I know from my experience that is not true, however I do not claim I am achieving PC, I also can't say my barrel is stopped, since I can shoot multiple lot speeds without adjusting the tuner and if the lots are consistent they will have same POI.

What I have learned is that the biggest factor is the lot you are shooting will be the key factor when shooting, in this case 50 & 100yds. if your rifle is really tuned and the lot is capable it will shoot consistently well at both 50 & 100 yds.. without touching the tuner.

And yes I know what Varmint Al have written and others on PC. but I go by what I see and can achieve as my targets can only tell me if what I am doing is right or not. in other words, I shoot and take what works and disregard everything else.

Lee

 

[Idaho-Lefty]

I think it has to do with, the slightly HIGHER, MV of, SOME, std velocity, Target ammo, doing / grouping, "descent" at 50 yds, AND HOLDING those "good" ( but, NOT exceptional ) groups to, the 100 yard PLUS, range thru, a little, BETTER, bullet, "stabilization" due to,.. the Velocity. Personally, I LIKE about,.. 1070 to 1085 FPS for 100 and it, still groups OK at, 50.
SK Long Range, Std Plus and Match Extra come to mind,.. in MY Rifle !
But, I "may" be,.. FOS,.. on this !

 

[grauhanen]

I appreciate your explanation, Lee.

Many shooters using tuners find that once a tuner setting has been verified to work at 50 -- that is "really tuned" as you put it -- it doesn't need adjustment from lot-to-lot or when switching to 100 yards. There's something important in that experience.

How tuners actually work seems to remain shrouded in some degree of mystery. Trying to figure it out can be a challenging exercise and I'm reminded what Jerry Stiller said about them about five years ago.

Tuners. They do something to help guns of all kinds shoot better. Exactly how? NOBODY really knows all the answers. Some is obviously vibration and structurally based. Some of it may be due to node location changes, frequency changes or dampening. One thing for sure, that is not all of it. If it was, then 0.005 of an inch movement of the mass on the end of the barrel would not have the affect that it does. The other thing about barrel vibrations. IT TAKES TIME TO SET UP STABLE VIBRATION PATTERNS. A lot longer time than the bullet is in the barrel. The whole antenna theory and fancy figures about very stable waves explaining how the barrel vibrates are basically true, they just don't get set up until AFTER the bullet is long gone and in general, really don't apply to our problem. Varmint Al's simulations of how the gun looks during firing is most likely very close to the reality. In the end, believe what you like. Explanations by uneducated meter readers or well thought out analysis and simulation by people with masters degrees or PHDs that can determine motion well enough to shoot probes to other planets. http://www.rimfireaccuracy.com/Foru...pensation-and-other-important-accuracy-issues

If the Varmint Al explanation of PC as explaining how tuners work is oversimplified, incomplete, or inapplicable, and if Calfee's "stopped muzzle" explanation is more than a failure of expression, terminology, and understanding of how a tuner works, then many readers can take refuge in the idea that we are not alone in failing to articulate how and why tuners work.

Thanks again, Lee.

 

[Hi-NV Shooter]

I appreciate your explanation, Lee.

Many shooters using tuners find that once a tuner setting has been verified to work at 50 -- that is "really tuned" as you put it -- it doesn't need adjustment from lot-to-lot or when switching to 100 yards. There's something important in that experience.

How tuners actually work seems to remain shrouded in some degree of mystery. Trying to figure it out can be a challenging exercise and I'm reminded what Jerry Stiller said about them about five years ago.

Tuners. They do something to help guns of all kinds shoot better. Exactly how? NOBODY really knows all the answers. Some is obviously vibration and structurally based. Some of it may be due to node location changes, frequency changes or dampening. One thing for sure, that is not all of it. If it was, then 0.005 of an inch movement of the mass on the end of the barrel would not have the affect that it does. The other thing about barrel vibrations. IT TAKES TIME TO SET UP STABLE VIBRATION PATTERNS. A lot longer time than the bullet is in the barrel. The whole antenna theory and fancy figures about very stable waves explaining how the barrel vibrates are basically true, they just don't get set up until AFTER the bullet is long gone and in general, really don't apply to our problem. Varmint Al's simulations of how the gun looks during firing is most likely very close to the reality. In the end, believe what you like. Explanations by uneducated meter readers or well thought out analysis and simulation by people with masters degrees or PHDs that can determine motion well enough to shoot probes to other planets. http://www.rimfireaccuracy.com/Foru...pensation-and-other-important-accuracy-issues

If the Varmint Al explanation of PC as explaining how tuners work is oversimplified, incomplete, or inapplicable, and if Calfee's "stopped muzzle" explanation is more than a failure of expression, terminology, and understanding of how a tuner works, then many readers can take refuge in the idea that we are not alone in failing to articulate how and why tuners work.

Thanks again, Lee.

You're welcome, if you want examples of results I have seen. go to RFC and in the Rimfire benchrest shooting sub-forum I started a thread on this same subject about same tune at 50yds. can't be at 100? I believe the results I have gotten, is good evidence on my statement about ammo being a big factor.

Lee