Group convergence with .22LR - yea or nay?

[_Shorty]

I was looking forward to how you'd pick and choose and misunderstand things he said, Glenn, and you didn't disappoint. Perhaps that's not entirely your fault, as I did not share what I had written to him, so some of the things that he's saying in response to what I said might not even seem like it is in response to anything, exactly. He does, in fact, talk about both his own centrefire experience and the centrefire/rimfire questions I put to him. I do believe "In summary, I am open to positive compensation as a mechanism that barrel weights could perhaps influence, in general." is a direct response to when I was referring to Kolbe's tests and talking about specific aspects of it, such as adding weight to the barrel to serve as a tuner in order to favour the target distance. "Having said all that, convergence, aka positive compensation is a different thing. The concept of it is hard to argue, and there is historical precedent with the Lee Enfield rifle." Here, he literally says the concept of it is hard to argue, and the remainder of that sentence has to do with an instance of it from his own experience. This would seem to mean that he agrees it is a thing and that it is hard to argue against it. That the example he has first-hand experience with is a centrefire rifle is not confirmation that it does not happen with rimfire. In fact, he talks about how it is a thing with rimfire in that video when he brings up the Lapua test centre example. He does not say, as you think, that this is something that only randomly happens and is not repeatable. He simply says it is something they sometimes see. There's a big difference between the two. When you're only testing at 50 m and 100 m, as the test centre does, it is possible that there only seems to be convergence with some lot numbers in some rifles. I contend that if you repeat testing with the same rifle and lot number that it will always show the same behaviour. And if you tested at more distance increments you'd see it happening basically all the time. The only time it shouldn't happen is if shots are not all exiting on a barrel upswing. I have asked him a few more things in reply to what he said. We'll see if he takes the time to reply again or not. I'll gladly share a subsequent reply from him if one comes.

I bet if I shot multiple groups at 40/60/80/100 yards in zero wind, every Monday of the year, my groups would all average out to be smaller at 40 and larger beyond.

Rimfire ammo has so many variables out of our control.

It depends on how you're measuring things, now, doesn't it? 1 MOA at 40 yards is roughly 0.4". 1 MOA at 60 yards is roughly 0.6". 1 MOA at 80 yards is roughly 0.8". And finally, 1 MOA at 100 yards is roughly 1". While 0.4" is smaller than 0.6", and 0.6" is smaller than 0.8", and 0.8" is smaller than 1", they're all 1 MOA. So do they increase in size as you go further out or not? A measurement that doesn't take the distance into account says they get bigger at each step, with the size in inches simply growing each time. But a measurement which takes distance into account, an angular measurement like MOA, says they're all the same size. Here are two examples of 50-shot groups at silhouette distances of 40 m, 60 m, 77 m, and 100 m with an Anschutz 1712 silhouette rifle. In one case the smallest group mean radius is at 60 m, and in the other the smallest group mean radius is at 77 m. And if the same test were carried out over and over with the same rifle/ammo pairings the result would remain similar, since this behaviour is inherent to the pairing of that rifle and that lot number of ammo. That's how they behave when paired together. I've seen this over and over in my testing. This indicates the convergence distance with that rifle and that lot number of Eley Club Biathlon is closer than with that lot number of Eley Club. One looks to be happening somewhere near the 60 m region, and the other looks to be happening near the 77 m region. If you tested at smaller distance increments you could narrow it down even more if you wanted to. One thing to take note of with regard to your comment is that the 40 m Eley Club mean radius is the largest of the four distances for that ammo, despite being the closest distance.

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

Eley Club
40 m - MR 0.769 MOA
60 m - MR 0.510 MOA
77 m - MR 0.500 MOA
100 m - MR 0.739 MOA

Eley Club Biathlon 40 m


Eley Club Biathlon 60 m


Eley Club Biathlon 77 m


Eley Club Biathlon 100 m


Eley Club 40 m


Eley Club 60 m


Eley Club 77 m


Eley Club 100 m

 

[jimbo14]

It depends on how you're measuring things, now, doesn't it? 1 MOA at 40 yards is roughly 0.4". 1 MOA at 60 yards is roughly 0.6". 1 MOA at 80 yards is roughly 0.8". And finally, 1 MOA at 100 yards is roughly 1". While 0.4" is smaller than 0.6", and 0.6" is smaller than 0.8", and 0.8" is smaller than 1", they're all 1 MOA. So do they increase in size as you go further out or not? A measurement that doesn't take the distance into account says they get bigger at each step, with the size in inches simply growing each time. But a measurement which takes distance into account, an angular measurement like MOA, …. (Snip)

Yes, I understand about MOA. I deal with trig equations all the time in my day job.

Cool pics too, but to me they show the variance of rimfire ammo, and I have a hard time drawing conclusions when I see fliers like that.

50 shot groups are great, but let’s see a large collection of them. I won’t draw any conclusions until I see a ton of data.

I’m not asking you to provide a bunch of info, but just that I will need to see evidence of repeatable behaviour before I sign onto anything.

I’d love to see myself grabbing a box of Lapua Long Range and being able to consistently shoot say 0.4 moa groups at 60m while only being able to do 0.6 moa at 40m. And able to demonstrate this on any calm day at the range that I wish. I would like the physics of that.

 

[_Shorty]

Yes, I understand about MOA. I deal with trig equations all the time in my day job.

Cool pics too, but to me they show the variance of rimfire ammo, and I have a hard time drawing conclusions when I see fliers like that.

50 shot groups are great, but let’s see a large collection of them. I won’t draw any conclusions until I see a ton of data.

I’m not asking you to provide a bunch of info, but just that I will need to see evidence of repeatable behaviour before I sign onto anything.

I’d love to see myself grabbing a box of Lapua Long Range and being able to consistently shoot say 0.4 moa groups at 60m while only being able to do 0.6 moa at 40m. And able to demonstrate this on any calm day at the range that I wish. I would like the physics of that.

That's why mean radius is used. That's why circular edge probable is used. Because variance is a thing. So you use a general takeaway that represents most samples. Something that characterizes the general behaviour. Outliers will always exist. The scientific community doesn't use statistics for no reason, after all. If you want to see it for yourself then by all means test it yourself. I have been encouraging others to run the test themselves. I'm not the only one that is capable of gathering data.

50-shot groups leave a reasonable margin of error or something like +/- 12%. Upping that to 100 shots brings that down to about +/- 8%. If you want to shoot a brick at each distance that'll drop it down to about +/- 3.7%. And 1000 shots each still leaves it at around +/- 2.6%. You'll need to shoot around 7000 shots to bring that under +/- 1%. And two full cases for 10,000 shots each still only brings that down to +/- 0.8%. So how much is enough?

When it's just lot testing for silhouette like that test was, I'm usually happy enough with 50 shots. When I lot test for benchrest I'm pretty happy with 100. Obviously the more you do the better your answer gets, but you have to draw the line somewhere. I guess it depends what you're trying to determine at the time. At the time I shot those, that's all I was doing was testing lot numbers for silhouette, and 50 was good enough for me for that purpose. If you need 10,000 shots per distance to convince yourself of whether or not convergence happens, by all means, I'd love to see the 10,000-shot groups when you're done.

 

[grauhanen]

Despite an absence of outside confirmation, support or verification of his claims, Shorty is stubbornly sticking to his guns, maintaining that convergence regularly happens with .22LR. It doesn't.

Shorty says his math and silhouette shooting proves it. Unfortunately it seems no one else claims to have proved it.

Even when Shorty thought the Litz interview video on Mach Trimming supported his claim, it turns out it doesn't. When .22LR convergence happens at testing facilities it's an unusual and random occurrence. It isn't regular and isn't repeatable on demand.

Litz modeled how this might be explained. His best answer was that it's the result of a corkscrew trajectory that gets smaller with distance.

It's not useful to continue this back and forth with Shorty. He'd sooner die on this hill rather than concede that there is no support for his claim about .22LR convergence being a regular thing.

 

[_Shorty]

Your confidence in your ignorance is amusing, Glenn.

 

[Terrible Tim]

I know this is center fire, but is there any reason .22LR would not behave similar?

From the Ruger Forum:

Does a Bullet Stabilize Immediately?​

 

[_Shorty]

I know this is center fire, but is there any reason .22LR would not behave similar?

I would imagine the same thing happens, but I would think it would be much less pronounced since we are living in the subsonic realm with 22 LR. At least, when we talk about target shooting we usually are, since we don't tend to do any target shooting with supersonic ammo. The amount of drag present with subsonic vs. supersonic is quite different. I believe the amount of drag present with supersonic centrefire shots is responsible for magnifying this effect, as well as being the reason it self-corrects as quickly as it does. When you start off subsonic, any yaw that is present isn't going to cause this phenomenon to occur with as much magnitude since the magnitude of the drag itself is so much lower.

 

[Licensed to kill]

Curious, how were these test strings fired? What order were they fired in, how much time between shots, were the different ranges shot one shot at each range, then the second and so on or on range completed before moving to the next or…?

 

[_Shorty]

Curious, how were these test strings fired? What order were they fired in, how much time between shots, were the different ranges shot one shot at each range, then the second and so on or on range completed before moving to the next or…?

I would've started with a clean rifle in the morning and shot the targets in order with one ammo, and started with a clean rifle on another morning with the other ammo and done the same thing. I wouldn't be mixing ammo as that would taint the results. I want to know how the ammo itself performs, not how it performs when mixing and matching lubes from shot to shot.

 

[Licensed to kill]

I would've started with a clean rifle in the morning and shot the targets in order with one ammo, and started with a clean rifle on another morning with the other ammo and done the same thing. I wouldn't be mixing ammo as that would taint the results. I want to know how the ammo itself performs, not how it performs when mixing and matching lubes from shot to shot.

I see. Thank you for the reply

 

[_Shorty]

Brian Litz doesn't seem to have much issue with my silhouette test showing the Eley Biathlon and Eley Club results with 50 shots at each distance, by the way.


He's once again mentioned his corkscrew idea. I don't think I agree with his idea about aiming more carefully when shooting at a longer distance since I was using OnTarget's #201 target that has diamonds that you can use to line up the crosshairs rather accurately no matter the distance.

https://ontargetshooting.com/wp-content/uploads/2018/08/TDS-Target-Style-201-791x1024.jpg

While he does think adding weight to the muzzle can be helpful, he's still not finding tuners to his liking as he thinks there isn't enough weight to change things. He seems to think you'd need to change the weight a lot more in order to get the necessary effects. I don't think the results from my barrel simulator agree with his thoughts on that matter, though.



He's mentioned mach trimming again, though I don't think there's anything to that for most target shooters since we tend to avoid ammo that starts off in the supersonic region.

 

[Williwaw]

Thanks for sharing this Shorty, looks like you have caught his interest.

I believe I'm in agreement with you that for our purposes barrel movement repeats. I'm suspicious that variations in our set ups may alter the entire rifles response which could influence the barrel which, on its own, would otherwise be relatively consistent.

I don't have any feel for the range of barrel exit times for a specific lot of ammo round to round and day to day. I see these two factors as the key ones regarding Litz's speculation on whether tunes are temperature stable.

 

[_Shorty]

I'm of the opinion that Litz hasn't done enough testing in the rimfire tuning arena to have opinions as strongly held as he does, frankly. At least, any testing that he's made public isn't enough. Who knows if he's done more that he just never reported on, though I kind of doubt he has. Given it seems 99% of what he does centres around the centrefire world this isn't too surprising. While he seems open to some of the theories while still voicing his doubts with certain aspects it seems to me he would do well to carry out a lot more testing on that side of things before forming such strong opinions. I'm in the middle of updating my simulator to allow inputting a temperature variable so I can demonstrate how much of a difference in movement there would be between, oh, 25 C and 0 C, for example. I don't think there's going to be as much of a difference there as he suspects. The difference in barrel length for a 26" barrel between those two temperatures is about 0.008", and I don't think the movement characteristics are likely to change very much. It might only change it in phase by maybe 0.5% or something. We'll see.

While I agree that reasonable temperature swings will affect ammo behaviour, I think this also varies from ammo to ammo. For example, I carried out some tests with CCI SV in the silhouette gun since it showed pronounced differences in performance in the summer versus the winter. During winter practice and matches I tried using self-heating hand warmers to keep the ammo warm in a lunch box, as well as the loaded magazines in my pocket. And even squished some of them in between the chamber area of the barrel and the scope to keep the chamber warm. This all kept the ammo's powder and lube a lot closer to the temperatures they'd see on 20 C days during the warm part of the year while it was below freezing with snow on the ground. And the ammo did indeed perform way better. Left to approach ambient temperature on days like that the stuff would start throwing really, really horrible fliers at an alarming rate, with those fliers all dropping way, way low. You'd see dirt fly way in front of the silhouette target stands quite often. It was incredibly frustrating. But the handwarmer tests stopped that from happening, and it seemed to be shooting as it usually did on warm days.

But I never had any similar issues with Eley Sport or Club. They didn't seem to really mind the cold. The performance may have differed in some way, but not to the extreme of the CCI SV's change. Not to the degree that I even noticed. Maybe if I did a bunch of target tests and chronoed it all I'd see some difference from freezing days to warm days. I don't recall having ever done that, though. The only temp tests I remember doing were the CCI SV handwarmer ones. Well, other than testing a handful of different biathlon rounds compared to the usual ammo I'd use to see if there was any point in buying the biathlon stuff for the winters we see here, for the silhouette matches. For silhouette it didn't seem to matter enough to bother, for me. Maybe it doesn't get cold enough here to see more meaningful differences between Eley Club and Eley Club Biathlon. It's rare to be very far below freezing here.

 

[Williwaw]

I have the same expectations of Litz's rimfire experience.

Regards ammo performance in the cold ... I have to be a bit reserved here because over the last few years I've bought three increasingly respectable rifles, moved up to a NF Comp and shifted from SK to Lapua. And, I like to think, improved as a shooter. The long and short of that is that I'd best hold my conclusions loosely. That said, to date it has to be below -16C before I see trouble. And I keep my ammo warm.

Appreciate your post. That tidbit of 0.008 per 25C temp change gives me a reference for testing tuner positions at different temperatures.

 

[_Shorty]

I've got my simulator working with a temperature input now. I can send you some figures based on the last barrel and tuner data you sent in a DM later on if you like. I can probably figure out how much it would likely have to move in order to retain behaviour with a bit of trial an error on the inputs. Then you could test whether or not that lines up with the real world tuner adjustments.