Chronograph data and its effects

[_Shorty]

In another recent thread it was a key point you insisted was true. This is what you wrote: "I said if you find the distance that a given ammo shoots its best at then you will also find it will shoot worse at every other distance. This is 100% true."

I can understand if you've reconsidered.


Post #6 above offers two explanations, only one of which seems plausible.

The idea that any ammo/rifle/tuner combination performs optimally at one specific distance is correct if positive compensation accurately explains how tuners work.

The idea that with no tuner involved any ammo and rifle will perform optimally at only one distance is not correct. Ammo is not distance-specific. Ammo that shoots very well at 100 will shoot very well at 50. But ammo that shoots very well at 50 may not shoot similarly at 100. Below is a brief explanation.

Since at least 1909 with the publication of Franklin Mann's book The Bullet's Flight From Powder to Target it's been known that there is a non-linear growth rate in group sizes as distance increases. In other words, groups get bigger or worse (MOA-wise) as distance grows.

In addition to gravity, a major cause of increasing group dispersion over distance is bullet imbalance. This is confirmed by Harold R. Vaughn in his 1998 book, Rifle Accuracy Facts.

It's worth noting that with .22LR bullet balance is a greater problem than with centerfire. This is because .22LR soft lead projectiles are likely to experience more imbalance than jacketed centerfire bullets.

Since group dispersion is non-linear, that is to say groups get bigger and bigger with distance (MOA-wise), no .22LR ammo can be a better performer at longer distances (MOA-wise) than at closer ones.

If groups get worse with distance, no ammo can be more optimal at a longer distance than a shorter one.

Obviously I was talking about in the same rifle. You don't seem to pay attention very well. Sorry, man, but once again basic ballistics dictates that you are incorrect here. It doesn't matter if you have a tuner on the muzzle or not, the physics involved is still the same. The tuner just changes one of the factors. As I've already tried to get you to do many, many times, go test several different ammo at a handful of different distances from the same rifle. You will find exactly what I said you'll find, that they don't all shoot best at the same distance. And the reason is precisely what I've laid out for you several times and had to repeat here again. I'll word it yet another way for you now. Convergence is another word for tuning. When you tune you are changing where convergence happens. And when you are not using a tuner the convergence distance is dictated by the rifle and ammo pairing. Every pairing has the potential to be quite different. I have, on many occasions, over the years done lot testing before a bunch of us all had to buy ammo at the same time. We would all shoot the same handful of lot numbers from our various guns. They all performed a little differently and preferred different lots for different distances. And we didn't all buy the same lot number as a result. Because each rifle/ammo pairing converges at a different distance. That's just how it works, man. You don't even understand what you said in your own post here, because you contradict yourself due to that misunderstanding. "There is a non-linear growth rate in group sizes as distance increases." is literally just another way of saying what I am saying. I don't have enough palms to facepalm with, here, for the amount of whooshing over your head that is happening. Sheesh.

All rifles will have shots converge at a given distance with a given ammo. That convergence distance will likely be different with every ammo variant you try due to the physics involved. And a tuner lets you move that convergence distance, hopefully to the distance you're actually placing your target. That is literally its purpose.

edit: What happens if you test at 50 yards, 100 yards, 150 yards, 200 yards, and 250 yards with an ammo/rifle pairing that happens to converge at 150 yards? You'll get a certain MOA of dispersion at 50 yards. At 100 yards you'll get less dispersion than you did at 50 yards. And at 150 yards you'll get less dispersion than you did at 100 yards. And at 200 yards you'll get more dispersion than you did at 200 yards. And at 250 yards you'll get more dispersion than you did at 200 yards. That could be described as non-linear growth as distance increases. Switch ammo and the new rifle/ammo pairing might converge around 150 yards again, or it could converge at 50, or 250. The only way to know is to test. And wherever the convergence distance is for that pairing, there will be more dispersion the more you move closer/further from that distance, with a caveat. Past the convergence distance it will only continue growing in dispersion. The caveat being that between the rifle and the convergence distance the dispersion will grow until a certain point, and then begin shrinking until it reaches the convergence distance. I haven't actually calculated it before, but since we're talking about a parabolic trajectory, I don't think the maximum dispersion point would be at halfway between the rifle and the convergence distance. It wouldn't be difficult to figure out at which fraction of the rifle-convergence distance that maximum dispersion point was if one took a few minutes to play with a ballistics calculator, though. I'd want to guess it'd be somewhere closer 2/3 of the distance to the convergence point than 1/2, but that is indeed just a guess. For that matter, you can kind of estimate it from the curves of the two shots that converge at 50 yards in this graph I shared before.



Looks like it'd be somewhere in the 28-36 yard region to me. Looking at actual drop numbers for both shots at a lot of intervals would obviously give a better answer.

 

[_Shorty]

The other thing he told me was that they always attempted to tune/achieve positive compensation at the longest distance shot in their matches. I guess with a tuner you could get a setting for each distance. Having said that I have no experience with tuners.

When selecting lot numbers of ammo for silhouette I choose based on shooting results at turkeys at 77m and find what shoots best there for me. They're the hardest animal to hit in that game, as they're the smallest target, and the weirdest shape. So I want to get as close as I can to converging there. That will give me the best chance of hitting them. This also gives me the best overall convergence error at the other animals at 40 m, 60 m, and 100 m. Finding what shoots best at 77 m is the best compromise for that game.

Yes, but within certain limitations. The further out you place the target, the faster the barrel's upswing needs to be. So once you've dialed the tuner all the way in to setting 0 you may or may not still be in need of yet more adjustment depending on the distance involved. You might still need more. In which case, you'd need to switch to a lighter tuner.

edit: I should also note, that before I understood everything that was going on as I understand it now, I used to test ammo for silhouette at all four distances and check the dispersion at all four animals. As I learned more and understood more, I then settled on only bothering to test at turkeys at 77 m. And that's because convergence is a thing, and thus testing at more than one of the four distances for silhouette is a waste of time and ammo. You learn all you need to know for that game at turkeys. That will get you the best results at turkeys, and minimizes the impact of convergence error at the other animals.

 

[Mysticprecision]

Great to see an informative CIVIL discussion on this very complicated topic. Lots of great info

For those competing in the rimfire PRS game, this is why I have advocated for testing at 100yds as a start... 50yds hides too many issues. Then the combo is confirmed at a good long range, 300 to 350yds just to make sure that the trajectory you expect actually happens in the real world.

One variable not discussed is bullet stability. If interested in shooting mostly beyond 200/250yds, maintaining a stable bullet is critical. When setup properly, the divergence is very small or much smaller then typical. The actual bullet itself has to be tested as each shape will respond to the adjustments differently.... spoiler, Lapua bullets seem to work consistently well at LR. Unsure if the bullet used in the CX/Midas family is the same as the LR/Super LR family (????) but these seem to work better then others

Enjoy the upcoming shooting season.

Jerry

 

[_Shorty]

I believe when I was chatting with Kevin Nevius about his chamber reamer design he mentioned that it should be suitable for any of the Lapua/SK ammo since they all use the same bullet, other than one of the Biathlon rounds. He was/is involved with some Lapua sponsorship shooters and worked with them quite a bit trying to get everything just-so with the reamer and ammo, down to saying he found ideal results with it cut to a very specific depth relative to the bullet.

 

[Mysticprecision]

Chamber is another rabbit hole and definitely plays an important role in accuracy. Whether a need for engraving or not, and the extent, I will leave for others to test to their satisfaction.

My chambers didn't have a hard engraving as I prefer to be able to extract a rd if a cease fire/time out is called. There is little to no gap though which I feel is enough for the needs of LR PRS. Around 1" 5rds groups at 100yds with preferred lots... good enough.

Nice to get confirmation that the Lapua/SK bullets are all the same shape.... wonder if there was QC inspection/Sorting like Eley does???? good ammo with all the ups and downs of grade and lot like any other match ammo.

YMMV

Jerry

 

[_Shorty]

IIRC, he didn't spec a whole lot of engraving. It was something like, cut it deep enough so that a round gently pushed in until it just makes contact is only sticking out by 0.073" and you should be good. He said the dimensions involved there seem to be very consistent with Lapua's various grades, and that's how all their competition rifles were done. That's just 30 thou after taking standard headspace into account.

 

[Chilly807]

The other thing he told me was that they always attempted to tune/achieve positive compensation at the longest distance shot in their matches. I guess with a tuner you could get a setting for each distance. Having said that I have no experience with tuners.

That would make sense, since as far as I know their tuning methods were static. Once you achieved the tune you wanted, say at 900 yds, or at 600 yds, you had to live with whatever else the rifle would do at a shorter range.
The longer range would have the largest amount of bullet drop for a given drop in velocity, so you'd want the rifle tuned at the longer range to minimize that effect. Less positive compensation at shorter range wouldn't be as costly score-wise since the bullets would be less likely to drop out of the bull as a result of being slower.
A friend of mine was actively shooting the old 303 Mk 4's back in the day, I expect he can shed some more light on this. It might actually be the same guy Longbow referred to. It's a fairly small group these days.

 

[grauhanen]

All rifles will have shots converge at a given distance with a given ammo. That convergence distance will likely be different with every ammo variant you try due to the physics involved.

The notion that convergence occurs may have been more widely accepted than it is now. For the general reader who may not be familiar with the idea of convergence, it is that at some distance downrange a group of shots that have been dispersing as expected will at some begin to converge, coming closer together to make a smaller group than they would have otherwise made.

To give an example to illustrate, geometry alone shows that natural dispersion is like the following. A group that is 0.5" at 50 is1" at 100, 2" at 200, 3" at 300, 4" at 400 and so on.



If convergence occurs, it means that in a 200 yard distance, for example, somewhere along the way, a group that is, say, 1" at 100 yards will be less than 2" at 200 yards or somewhere in between.



It can be demonstrated that barrel harmonics alone will with some ammo at some distance experience a reduction in vertical dispersion. But this is almost entirely in the vertical dimension. Group dispersion will require a reduction in group size in all directions, vertical and horizontal. With .22LR groups grow in size in all directions.

What's critical to keep in mind is that .22LR doesn't experience linear dispersion (groups that are 1 MOA at 50 are 1 MOA at 100 etc.). It experiences non-linear dispersion. This means groups get bigger MOA-wise as distance increases. This is illustrated in the diagram below. The orange line shows a non-linear dispersion with MOA increasing with distance.



The non-linear nature of .22LR dispersion explains why convergence doesn't happen. MOA-wise, results get worse with distance, never better.

This is not to say that convergence with .22LR never occurs. In testing facilities there are times when results (MOA-wise) are better at 100 meters than at 50. But these are relatively rare and unusual and they happen unpredictably. When such results are unpredictable, that indicates they are by accident. The reason they sometimes happen has to do with bullet imbalance. Sometimes the forces that normally cause dispersion by fluke or rare chance cause convergence.

 

[Leuchtkafer]

I was having some fun with Grok AI and figured why not throw this question at it? "Compare and contrast the “positive compensation” and “stopped muzzle” theories for .22 LR bench rest shooting". I had put Grok into "unhinged" mode, just because it makes the responses a little more fun and not so dry and academic Here's the answer I got:

"Alright, let’s dive into the wild and woolly world of .22 Long Rifle bench rest shooting theories—specifically, “positive compensation” versus “stopped muzzle.” Buckle up, because this is about to get unhinged in the best way possible, with barrels vibrating, bullets flying, and shooters arguing like it’s a family reunion gone off the rails!

Positive Compensation: The Barrel’s Dance Move

Imagine your rifle barrel as a whip-smart dancer, shimmying just right to make every bullet hit the same spot, no matter how fast or slow it’s moving. That’s the gist of positive compensation. This theory says that when a .22 LR bullet exits the muzzle, the barrel’s natural vibration (or “whip”) can be tuned so that slower bullets—lagging a bit due to lower velocity—catch the muzzle on an upward swing, while faster bullets zip out when it’s lower. The result? Vertical dispersion gets canceled out, and your shots cluster tighter than a pack of wolves on a deer trail.

• How It Works (Theoretically): As the bullet travels down the barrel, the recoil and pressure make the barrel flex like a diving board. A tuner (a weight on the muzzle) adjusts this flex so the muzzle’s angle at bullet exit compensates for velocity differences. Slow bullet? Muzzle tips up higher. Fast bullet? Muzzle’s lower. Boom—same impact point.
• The Gear: You’re tweaking with tuners, barrel harmonics, and sometimes stock bedding or action tuning. It’s like tuning a guitar string to hit the perfect note.
• The Claim: Advocates say this can shrink groups to mind-blowing levels, especially at 50 yards, where .22 LR bench rest shooters live and die by the size of their holes (we’re talking sub-0.2-inch groups).
• The Vibe: It’s dynamic, man! The barrel’s alive, moving with purpose, and you’re the maestro conducting this symphony of physics.

Stopped Muzzle: The Statue Approach

Now picture this: the barrel’s a stoic statue, standing dead still when the bullet says goodbye. The stopped muzzle theory claims that with the right setup—usually a heavy tuner or muzzle device—you can dampen the barrel’s vibrations so much that the muzzle barely twitches when the shot fires. No movement, no variation, just a rock-solid launch pad for every bullet, velocity be damned.

• How It Works (Theoretically): The tuner’s weight and position are dialed in to kill the barrel’s harmonic dance party. The muzzle’s “stopped” (or close to it), so every bullet exits at the same angle, regardless of how fast it’s going. Vertical spread? That’s just the ammo’s fault, not the barrel’s.
• The Gear: Heavy tuners, sometimes blueprinting the action, and a barrel that’s often a chunky beast. Precision is king—think custom rifles that cost more than your car.
• The Claim: Devotees swear this delivers consistency tighter than a miser’s wallet. If the muzzle doesn’t move, you’ve eliminated one variable, leaving ammo quality as the last frontier.
• The Vibe: It’s all about stillness, control, and brute-force engineering—like a bouncer telling barrel vibes to sit down and shut up.

Compare and Contrast: Let’s Break It Down

Similarities

• Goal: Both theories aim to shrink group sizes in .22 LR bench rest shooting, where a gnat’s whisker can mean the difference between glory and “nice try, buddy.”
• Tools: Tuners are the star players in both camps. Whether it’s a Harrell’s or a custom job, you’re slapping weight on that muzzle to mess with physics.
• Context: They’re born from the same obsessive world of rimfire accuracy, where shooters chase perfection at 50, 100, or even 200 yards.
• Debate Fuel: Both have die-hard fans and skeptics who’d rather fistfight than agree, making forums like Benchrest Central or Rimfire Central a popcorn-worthy circus.

Differences

• Philosophy:
  • Positive Compensation: The barrel moves, and that’s a good thing. It’s about timing the muzzle’s motion to match bullet speed—like a trick shot in pool.
  • Stopped Muzzle: Movement is the enemy. Stop the muzzle dead, and you’ve got a stable platform, no fancy timing required.
• Mechanism:
  • PC: Relies on the barrel’s natural whip being tuned so slower bullets get a lift, and faster ones don’t. It’s a balancing act of harmonics.
  • SM: Dampens that whip to near-zero. The muzzle’s angle doesn’t change, so velocity variation shows up as pure drop, not angular weirdness.
• Evidence (or Lack Thereof):
  • PC: Backers point to tests showing tight groups with velocity spreads, claiming the barrel’s compensating. Critics say it’s just good ammo and luck—where’s the smoking gun (pun intended)?
  • SM: Supporters flaunt targets with vertical stringing but no angular scatter, saying a stopped muzzle proves itself. Doubters argue no barrel’s truly “stopped”—it’s just less wiggly.
  • Practicality:
    • PC: Requires constant tuning for conditions, ammo lots, and ranges. It’s finicky—think of it as a high-maintenance partner.
    • SM: Once dialed in, it’s supposedly set-and-forget across distances (50 to 200 yards, no tweaks). Less drama, more plug-and-play.
  • Criticism:
    • PC: “It’s a myth! No barrel can perfectly sync with every bullet!” cry the naysayers. Plus, wind and ammo inconsistency muddy the waters.
    • SM: “Stopped? Ha! It’s still moving, just slower. And good luck finding ammo consistent enough to prove it,” retort the haters.

The Unhinged Take
Positive compensation is like a caffeinated acrobat flipping through the air, hoping to stick the landing every time. Stopped muzzle is the grumpy old guy in the corner, arms crossed, refusing to budge an inch. Both promise you’ll shoot like a god, but neither’s got a trophy case full of undisputed proof. Bench rest shooters have been brawling over this for years—some swear by one, some by the other, and some just shrug and buy better ammo.
In the end, it’s a .22 LR cage match: whippy barrels versus stone-cold muzzles. Pick your fighter, tune your rig, and let the targets tell the tale. Me? I’d say grab a beer, shoot both ways, and laugh at the chaos—because in this game, the only winner is the guy who doesn’t overthink it too damn much!"

Anywho, I've got a set of targets I shot at 100 yards over a chronograph some time ago that I never got around to scanning and making a post about, long debated if it'd even be worth sharing, but along comes this thread and now I'm thinking perhaps I'll try to get around to it. I'm a little pressed for time to do so until about a week from now though.

 

[grauhanen]

Anyone wishing to look further into the idea of convergence should look at Chapter 2 of Bryan Litz's Modern Advancements in Long Range Shooting, Volume II. He originally began to try to answer the question how convergence happens. He found that the better question was does convergence actually happen at all. After all his testing and consideration of the various theories that tried to explain convergence, he concluded that all that effort was irrelevant.

 

[grauhanen]

Rabid ... er, Leuchtkafer, that's a nice summary of the competing ideas.
____________________________

If PC explains how tuners do their thing, then the same setting doesn't work at all distances. This has implications for shooters who use them in disciplines with targets at a variety of distances.

Of course, there's another aspect of using a tuner at various distances. It is difficult to show reliably how well a tuner works at long distances. At the same time, it is equally difficult to show that a tuner doesn't work at long distances.

 

[Williwaw]

Note that any amount of vertical tuned out by PC at a shorter distance will be removed at greater distances. So even when distances are so great that atmospherics complicate confirmation you can still benefit from a tuner at longer distances.

Check me on that Shorty. Makes sense to me but I was wrong once before.

 

[_Shorty]

Anschutz 1712 silhouette rifle and some examples from silhouette ammo lot testing.

Eley Biathlon mean radius
40 m 0.536 MOA
60 m 0.512 MOA
77 m 0.575 MOA
100 m 0.885 MOA

Conclusion: This lot number of Eley Biathlon converges somewhere between 40 m and 77 m with this rifle, likely very close to 60 m. This was the best performing ammo variant in that rifle for cold weather that time around, and I ended up buying a case of it for the cold weather matches, even though I didn't care for where this one was converging. I want it converging close to 77 m. But it was still the best compromise of the cold weather lots I had to choose from at that time.

Eley Club mean radius
40 m 0.769 MOA
60 m 0.510 MOA
77 m 0.500 MOA
100 m 0.739 MOA

Conclusion: This lot number of Eley Club converges somewhere between 60 m and 100 m with this rifle, likely very close to 77 m. This was the best performing ammo variant in that rifle for warm weather that time around, and I ended up buying a case of it for the warm weather matches.

Image links:
Eley Biathlon 40 m paper
Eley Biathlon 40 m stats
Eley Biathlon 60 m paper
Eley Biathlon 60 m stats
Eley Biathlon 77 m paper
Eley Biathlon 77 m stats
Eley Biathlon 100 m paper
Eley Biathlon 100 m stats

Eley Club 40 m paper
Eley Club 40 m stats
Eley Club 60 m paper
Eley Club 60 m stats
Eley Club 77 m paper
Eley Club 77 m stats
Eley Club 100 m paper
Eley Club 100 m stats

Bryan Litz is a pretty knowledgeable guy, there's no doubt about that, but that isn't to say he's infallible. He's not only wrong about convergence, he also thinks tuners don't work at all. When he tested tuners it was immediately obvious to anyone familiar with benchrest shooting and tuner usage that he had absolutely no idea what he was doing when it came to tuners. The equipment he chose and how he did the test was ridiculous. He's right about a ton of things, but he's also wrong about some things. And these are two examples where he is indeed wrong. And the convergence issue is the stranger of the two, as understanding convergence comes from understanding basic exterior ballistics. At least with tuners it requires some more knowledge to figure out, and he can't be faulted for making ignorant assumptions that happened to be horrible. He just didn't know any better. But with convergence he should know better. The way projectiles fly through the air involves behaviour that dictates convergence must be a thing. That his experiment would seem to be faulty is his fault, not the fault of physics. Physics will always do what it should be doing.

 

[_Shorty]

Note that any amount of vertical tuned out by PC at a shorter distance will be removed at greater distances. So even when distances are so great that atmospherics complicate confirmation you can still benefit from a tuner at longer distances.

Check me on that Shorty. Makes sense to me but I was wrong once before.

If I'm understanding you correctly, I don't think you're visualizing things quite right. If you dial in PC for 50 yards and then go shooting at 200 yards you're adding vertical at 200 yards. Your tune moves the convergence point to 50 yards. It doesn't remove vertical. And with that convergence point moved to 50 yards, every yard you go past 50 yards you're adding more and more vertical. Between 0 and 50 yards the drop delta starts at 0, obviously, and grows until around halfway to 50 yards, and seems to peak at about 0.04", maybe getting close to 0.05". It then begins shrinking again. And since you've tuned for 50 yards, the drop delta when you reach 50 yards is zero. Same hole at 50. But if you keep going, at 75 yards the drop delta has grown to 0.13", and at 100 yards it has grown to 0.32", and at 125 yards it has grown to 0.59", and at 150 yards it is 0.94", and at 175 yards it is 1.38, and finally out at 200 yards it has grown to 1.88".



ok, so what if you regularly shoot at distances between 50 yards and 200 yards? Should you then tune for 200 yards?



That'll obviously move your zero drop delta point to 200 yards. This makes it easier to see what happens between the muzzle and your target distance, since we're now magnifying what happens between those two points. Also answers quite well where the maximum divergence happens between the muzzle and the tuning distance. I thought it might be closer to the 2/3-distance mark, at least I think that's what I said earlier. But this confirms it is pretty much halfway. Here we see the drop delta max out at 0.62" from around 90 yards to 110 yards. At 50 yards it is 0.47", and at 75 yards it is 0.58", at 100 yards it is 0.62", at 125 yards it is 0.58", at 150 yards it is 0.46", and at 175 yards it is 0.27". So it grows from muzzle to 100 yards, and begins shrinking again until the tuning distance. And as in the previous image, if you continued on the delta would begin growing from that point onwards, getting bigger all the time.

edit: If you're regularly shooting at various distances you'd be wise to figure out a separate tune for each one, if that is even possible. It may not be possible. There might be too many distances to worry about, or you may not even be able to tune for certain distances. There are physical limits given a particular barrel length and contour, and the tuner you pair it with. If you can't tune at all, such as is the case with silhouette, you've got to hunt for ammo that is the best compromise, which is whatever shoots best at 77 m. If you can tune, such as PRS, since you're going to be shooting at various distances you'll have to decide on a compromise that should give you the best all-around results for your range of distances. If silhouette testing is any indication, that's likely going to be somewhere around 75% of your entire range of distance possibilities.

 

[grauhanen]

Bryan Litz is a pretty knowledgeable guy, there's no doubt about that, but that isn't to say he's infallible. He's not only wrong about convergence, he also thinks tuners don't work at all. When he tested tuners it was immediately obvious to anyone familiar with benchrest shooting and tuner usage that he had absolutely no idea what he was doing when it came to tuners. The equipment he chose and how he did the test was ridiculous. He's right about a ton of things, but he's also wrong about some things.

Litz's .22LR tuner work was ill-conceived and poorly executed. He might admit that he's on much firmer ground with centerfire than with rimfire.

In any case, someone like Litz can be right about one thing and wrong about another.

Here's why convergence doesn't happen with .22LR -- except by accident. Group dispersion is non-linear. It is not 1 MOA at 50, 1 MOA at 100 and so on. Group dispersion or group size always gets worse with distance -- except by unpredictable chance.

The information you have given above for Eley Biathlon and Eley Club purports to show convergence. But the data has a major flaw that renders it invalid. The targets show results at different distances. But comparisons must be apples to apples. These results were obtained with different rounds, apples to oranges.

Any alleged convergence shown is not convergence with the same rounds. Different rounds can easily produce different results, even when they are from the same lot. (For the general reader this is why groups shot at the same distance with the same lot will vary in size.)

There seems to be only two ways to "prove" convergence. First of all the same rounds must be compared at different distances. One way to do this is to shoot through paper targets set up at different distances and then compare the group sizes at each one. This has the disadvantage of not only being awkward, but not impossible, to set up, but also risking some unknown degree of deflection by the passage of bullets through the paper target.

The better way is to compare results recorded electronically at two or more distances, which is what happens at testing facilities such as those of Lapua in Ohio and Arizona. At these locations the group sizes of the same ten shot groups are recorded electronically at both 50 and 100 meters. As a result, it's possible to compare the group sizes at 50 and 100 with the same rounds.

When rare examples of convergence happen, they are accidental, not repeatable. A comparison of 50 and 100 meter group sizes has shown that groups grew larger on average by a factor of 2.8 times -- with some rifles/lots being better or worse than others. Group dispersion with .22LR is non-linear. Groups get bigger (MOA-wise) as distance increases.

 

[grauhanen]

Note that any amount of vertical tuned out by PC at a shorter distance will be removed at greater distances. So even when distances are so great that atmospherics complicate confirmation you can still benefit from a tuner at longer distances.

Makes sense to me but I was wrong once before.

Perhaps what is reduced or eliminated at 50 yards/meters with a tuner -- the vertical dispersion caused by MV variation -- doesn't automatically happen again at further distances.

When a slower bullet and a faster one intersect at 50 they have different trajectories and will begin to diverge once past that distance. The rounds continue to have different velocities and nothing occurs to bring them back to converge at another distance.

 

[Williwaw]

When a slower bullet and a faster one intersect at 50 they have different trajectories and will begin to diverge once past that distance. The rounds continue to have different velocities and nothing occurs to bring them back to converge at another distance.

Thanks for trying but I'm sticking to my story. If a tune compensated for the difference in MV between two rounds at 50 yards that amount of vertical delta does not go away down range. Of course they do not converge at 100 yards but the vertical difference at 100 yards is diminished by the amount of vertical correction the tune supplied at 50 yards.

I'm going shooting ... haven't missed a day since mid Feb when we had a cold snap.

 

[_Shorty]

Litz's .22LR tuner work was ill-conceived and poorly executed. He might admit that he's on much firmer ground with centerfire than with rimfire.

In any case, someone like Litz can be right about one thing and wrong about another.

Here's why convergence doesn't happen with .22LR -- except by accident. Group dispersion is non-linear. It is not 1 MOA at 50, 1 MOA at 100 and so on. Group dispersion or group size always gets worse with distance -- except by unpredictable chance.

The information you have given above for Eley Biathlon and Eley Club purports to show convergence. But the data has a major flaw that renders it invalid. The targets show results at different distances. But comparisons must be apples to apples. These results were obtained with different rounds, apples to oranges.

Any alleged convergence shown is not convergence with the same rounds. Different rounds can easily produce different results, even when they are from the same lot. (For the general reader this is why groups shot at the same distance with the same lot will vary in size.)

There seems to be only two ways to "prove" convergence. First of all the same rounds must be compared at different distances. One way to do this is to shoot through paper targets set up at different distances and then compare the group sizes at each one. This has the disadvantage of not only being awkward, but not impossible, to set up, but also risking some unknown degree of deflection by the passage of bullets through the paper target.

The better way is to compare results recorded electronically at two or more distances, which is what happens at testing facilities such as those of Lapua in Ohio and Arizona. At these locations the group sizes of the same ten shot groups are recorded electronically at both 50 and 100 meters. As a result, it's possible to compare the group sizes at 50 and 100 with the same rounds.

When rare examples of convergence happen, they are accidental, not repeatable. A comparison of 50 and 100 meter group sizes has shown that groups grew larger on average by a factor of 2.8 times -- with some rifles/lots being better or worse than others. Group dispersion with .22LR is non-linear. Groups get bigger (MOA-wise) as distance increases.

You have literally no idea what you are talking about. I have shown you over and over and you still fail to understand reality. I've shown you the theory. I've shown you real-world results. Not just in this thread, but in many others where you didn't know what you were talking about. And you still don't know what you're talking about. You have literally no interest in learning anything. You have an idea cemented in your head and that idea will never change, regardless of what evidence or explanations you are presented with. You think you already know, despite evidence to the contrary being placed in front of you multiple times. You think many things are unexplainable, despite someone showing you the explanation and the real-world data that backs it up, on multiple occasions. It is sad.

"Any alleged convergence shown is not convergence with the same rounds." You really, really, REALLY need to learn about statistics. Not to mention I have already shown you the results of a test with all rounds going through four targets. You conveniently didn't comment on it because it showed you were blowing hot air. Physics is physics whether you understand physics. You do not understand physics. You do not understand ballistics, which is just a subset of physics. You do not understand guns. You wouldn't be here spouting the same misinformation over and over if you did. Shooting a lot of rounds at each of four different distances gives you statistical evidence of what occurs with each shot as it passes that distance. "But they're different shots." is not a good argument. It is barely an argument if I had only shot a single 5-shot group at each distance. But every single extra shot I take at each distance is another nail in the coffin of your argument. I've literally shot thousands of rounds at each of the four distances in silhouette in tests like this over the years. And I have OnTarget results for a good portion of it. But I'm not about to sit here and process and upload hundreds of targets and their attached statistics for you. It should suffice that I say "Here's a couple of examples from a much larger set that show the same kind of thing." since we're just two guys talking here. I shouldn't have to show you my entire hard drive to get you to understand and accept an idea. I've done my best to explain the idea, and following that up with an example of the data that supports it should be good enough. I'm not expending all this time and thought and energy in some strange attempt to fool you into thinking something that isn't so. I'm actually just trying to teach you, period. I don't get my jollies trying to trick you. I actually want you to learn more about something you've already shown interest in.

Taking samples from the entire dataset is sufficient when the samples are numerous enough, since the more samples you have, the closer you are to the actual answer. That's how statistics works. Examining four different distances and getting the right answer doesn't require a sample from all four distances for each shot. It would make the test shorter if you did have a sample from all four distances for each shot, yes, but taking many samples individually from each distance is just as valid if you take enough samples. Both cases would show you the same thing because we're talking about something that has a normal distribution. By definition that means if you take enough samples from any viewpoint you will eventually get a good idea about the entire picture. Do you even know what a normal distribution is? Do you understand that? Do you understand the implications of that? Because all these arguments you put forth are contrary to that. And for that reason they are invalid. For that reason they do not make sense. For that reason they do not hold water.

Statistics does a very good job of telling you how accurate a picture you have of something that is normally distributed. A 5-shot group doesn't tell you much because the amount of error is so great. Your 95% confidence window at just five shots is 0.603091-1.435802. That means the real answer could be anywhere from ~60% of your result to ~144% of your result. In other words, your result is practically useless. It doesn't really tell you anything because the error margin is much too large. Increase that sampling to 25 shots and your 95% confidence window shrinks to 0.834521-1.171609, which is a lot better. Now you're roughly +/-17% instead of 60+. Move to 50 shots and the window falls to 0.883711-1.119015, and at 100 it falls to 0.918038-1.083349, and at 250 it falls to 0.948144-1.052477, and at 500 it falls to 0.963291-1.036956, and at 1000 it falls to 0.974051-1.026139, and at a full case of 5000 it falls to 0.988426-1.011646, and at two cases, 10000 rounds, it is 0.991769-1.008259. Still a +/-0.8% error window after shooting two full cases of ammunition. You never know the exact answer. You just have a sample, and a window showing the confidence in your answer being representative. Tracking the same bullet through all four targets or shooting multiple rounds individually at each target would only reduce the test length to 1/4 and the ammo cost to 1/4. It wouldn't improve the answer. It would only satisfy your "Yeah, but..." tendency due to not understanding things properly. Describe both test scenarios to a physicist and they will tell you that both scenarios would be satisfactory and would indeed tell you the same thing providing you satisfy the requirements of the confidence window. 100 shots though all four targets at once would require 400 shots with the individual targets scenario, taking 100 shots at each target individually, and you'd learn the same thing with either scenario with the same amount of confidence in their answers. Literally. Because we're talking about normal distributions.

I gave you two examples that are representative. That should be enough to indicate that your idea might not be the correct idea. But you don't like the answer, so you start doing as much mental gymnastics as you can to try to discount actual evidence that doesn't suit you. This, coming from a guy that said "I get one SD and ES from one box of ammo, and the next box of the same lot I get a different SD and ES. So clearly the ammo isn't very consistent." It boggles the mind. Repeatedly saying "For the general reader..." doesn't mean you know what you're talking about. Showing and explaining theory and sharing real-world experimental results that support the theory would better indicate whether or not you have a solid understanding of something. "Convergence doesn't happen with 22 LR. Bryan Litz says so." Well, here's two examples of many showing that it does happen in the real world. "Nah, Bryan Litz!" Heh.

 

[Leuchtkafer]

Some men grow old, but never grow wise. Some never develop their emotional maturity beyond that of a toddler, either. I respect your altruism, Shorty, though there comes a time when one would be better served by no longer giving toxic individuals the time of day anymore.

 

[_Shorty]

Thanks for trying but I'm sticking to my story. If a tune compensated for the difference in MV between two rounds at 50 yards that amount of vertical delta does not go away down range. Of course they do not converge at 100 yards but the vertical difference at 100 yards is diminished by the amount of vertical correction the tune supplied at 50 yards.

I'm going shooting ... haven't missed a day since mid Feb when we had a cold snap.

Perhaps this will illustrate it a little better. Tuning distance left to right, and drop in inches for target distance top to bottom. 1060 fps vs 1085 fps, as before.


50 yd tune

75 yd tune

100 yd tune

125 yd tune

150 yd tune

175 yd tune

200 yd tune


Tuning distance is convergence distance. They all start with zero divergence at the muzzle, and halfway to the tuning distance they reach their peak height as well as peak divergence before converging, then at the tuning distance they converge, and beyond the tuning distance they diverge more and more as distance increases more and more. You seem to be saying that once you "dial out vertical" it remains gone, but that isn't what happens. You "dial out vertical" at just one spot, your tuning distance. Between the muzzle and tuning distance it grows half the way and shrinks the remaining half of the way. Then it is zero at the tuning distance. And after passing the tuning distance it just gets larger and larger. And here we have the absolute deltas so you can see the average delta for each tuning distance:



As I suspected earlier, the best average deltas happen when you tune for 75% of the total distance you'll be shooting when you'll be shooting at several distances. The average amount of vertical for the 150 yd tune is 0.28125", the smallest of all seven tuning distances.