Observations about .22LR ammo -- sometimes it can be weird

G

grauhanen

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I did a bit of shooting since late September. I was at the range four days out of five the first week of October, and except for later yesterday morning I had the place all to myself. I had the luxury of chronographing all the shooting I did since last Friday, October 1st. I saw some things that were surprising, some even strange. It's those things that got me thinking, and although I don't have any answers I’ll get to some of those strange things I observed later in this thread.

Experienced shooters will know everything that follows. Those readers who dislike wordy introductions may wish to skip this.

First some basics for those shooters who may wish some reinforcement.

This part is for newer shooters. This is for the shooter who is like I was five or six years ago, as I was just beginning to learn about shooting .22LR seriously. I wish I knew back then what I know now. It might have saved some confusion and exasperation, but never all of it.

Probably almost everyone has experienced frustration with .22LR shooting for accuracy and precision. (I understand the words aren’t necessarily synonymous, but I may at times treat them that way.) Between episodes of frustration, .22LR riflemen learn a few things about the ammo.

Shooters quickly learn that standard velocity .22LR ammo will almost always be more accurate than high velocity. They also learn that match ammo made by one of the big three .22LR ammo makers – Eley, SK/Lapua, and RWS – usually shoots much than other SV ammos. They may learn that the least expensive varieties of or “target” type of ammo – the SK varieties, Eley Sport and Club, for example, are often outshot by more expensive match grade ones. They know it doesn’t always play out that way, but it often does.

As rimfire enthusiasts burrow deeper into what’s often described as the rabbit hole of .22LR accuracy, they will often get the “best” rifles they can afford – rifles that have a reputation for shooting well, rifles that have the potential to shoot the best ammo as best as possible. They’ve come to understand that some makes of rifles tend to be consistently better performers. Many of these rifles aren’t hard to find, it just takes a bit of money to get them – Anschutz, RimX, and Vudoo are a few such good performers that are currently available new.

They’ve learned that what’s key to achieving the rifle’s potential for accuracy is getting the most appropriate ammo for their rifle. They’ve learned by now that the name on the box – whether it’s Center X or Tenex – doesn’t guarantee accuracy. That’s because not all CX or Tenex is the same. The performance of every variety of match ammo, be it Center X, Midas +, Eley Match, or Tenex, can be different. Performance varies by lot, the batches in which each variety of ammo is made. For the best match between rifle and ammo, no matter what name is on the box, shooters must lot test for the best results. They buy many different lots of the same variety of ammo, Center X for example, and test each lot to find which shoots best in their rifle.

But this is getting ahead of the game and it's not what this is about.
 
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Most typical shooters who haven’t been long on the journey on the road to rimfire accuracy probably rarely if ever lot test. They buy ammo as they need it or when they can afford to buy in quantity for use over a long period of time. They will get random lots of ammo. They may be lucky enough to get good shooting lots, but most of the time they will get average shooting lots, no matter what variety they get.

The basic things shooters will need to understand are the characteristics, the physics, the ballistics of .22LR ammo.

Below are some basic ballistics. Of course, there are almost always exceptions to rules and in a later post I’ll show anomalies or examples of when these basic “rules” don’t seem to apply. Readers already familiar with the basics may wish to skip this.

Every round in a box of ammo is probably unique. That is to say, very often no two bullets are exactly alike, no matter what name is on the box. Quite often the less expensive the ammo, the more unique each round is in the box.

Regarding muzzle velocity of .22LR ammo, no matter what figures are provided by the manufacturer about the muzzle velocity (MV) will be the actual MV in a particular rifle. The MV given by the ammo maker is a suggestion, a ballpark figure. The average MV in a rifle may be more or less than the average given by the manufacturer.

Furthermore, each round will have a different MV. Some may be the same, but most of them will differ from one another. That’s just the way .22LR ammo is. Not always but most often, less expensive varieties of ammo will have a wide range of velocities (extreme spread or ES) in a box, often more expensive ones will have a smaller ES.

Why is this important? Rounds with a faster MV will tend to strike higher on the target than those that are slower in flight. At 100 yards, for example, a ballistics calculator shows that a .22LR standard velocity bullet with an MV of 1070 fps should strike about .27” higher than a bullet with an MV of 1060 fps.



In other words, according to the ballistics, for each 10 fps difference between one round and another, there will be about one-quarter inch of vertical spread. A 40 fps difference between one round another results in 1” of vertical.

Good match ammo will have a velocity range or ES of about 30 fps or less. Ammo like that is not always easy to find. Significantly, there’s no guarantee that the price of the ammo or the name on the box means that the ES is low.

As a result, .22LR shooters looking for good accuracy and small groups will want ammo that has as low an ES as possible to help assure as little vertical dispersion as possible.
 
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The wind will also influence the ammo. The further the target, the more the wind will push the bullet.

According to the ballistics calculators, for each one-mph difference in a crosswind, a .22LR SV bullet will drift about .1” at 50 yards and .4” at 100 (see ballistics chart below). The further the target, the worse it gets. And to add to the challenge, a 1-mph change in wind velocity is barely noticeable.



In short, when there’s wind, even if it’s not a crosswind, there will be an effect on the POI of the bullet. The more the wind, the greater the horizontal spread or dispersion.

A final note about wind. With .22LR, the slower the bullet, the less the wind affects it. It’s counter-intuitive because it seems natural that the less time a bullet is in flight, the less the wind will affect it. With .22LR it doesn’t work that way. There’s a reason for this that can be provided should anyone want to know. But with .22LR slower is better in the wind. It’s not very significant at distances such as 50 or 100 yards.
 
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Now for some of the data collected. Readers should note that the figures obtained were with my two rifles, one a newer Anschutz 1913, the other a 1973-made 1411, originally a prone rifle which I have in an Anschutz benchrest-style stock. Both have exactly the same length barrels. If this ammo were shot through another bore, the muzzle velocities would likely differ.

The data shown below were obtained on September 28 and October 1, and October 5 -- 8. My area had a very calm spell, especially in the mornings. On the days I shot, the conditions were as close to ideal as is possible when shooting outdoors. On two of the five mornings there was only the occasional whiff of a slight breeze as registered on my wind flags or on the yellowing leaves of trembling aspens adjacent to the range.

Both of my rifles are good shooters. I shot some of the same lots with both rifles. I used a chronograph to record MVs for all the ammo that I shot on the October dates, using several lots of Center X and Midas +, one of X-Act and several lots of SK Rifle Match. I also tracked the location of each shot as I made it, although on occasion I couldn’t determine POI, especially when shots landed very close to each other.

Below is the chronograph data. The left side column shows the date and rifle used. The last three digits of the ammo lot number is given. Readers may note that the same lots produced higher MVs on average with one rifle, slower with the other.



On September 28 I shot many of the same lots, but I didn't use my chronograph. The target results at 100 yards are shown in the table below. The figures are the averages of all the ten-shot groups on a single target. Most averages are of four ten-shot groups, but a few from September 28 are averages of three ten-shot groups, and later two are of five ten-shot groups. They are indicated with asterisks.



Clearly, some Lapua lots were not as good as others, with some results quite ugly. The SK Rifle Match lots were not all equal either.
 
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One of the biggest sources of frustration for rimfire shooters is that sometimes the ammo doesn’t behave as it should.

To be sure, faster rounds tend to have a higher POI on the target than slower ones.

And smaller groups usually have a small group velocity spread or ES.




Of course, not all results were good. I shot plenty of targets that had disappointing groups.

Generally, larger groups tend to have a greater group ES than smaller groups.




The above targets show the difference between good and not-so-good lots of CX.

The best performing lot of Center X had a 17 ten-shot group average of .956”. Its chronograph data showed low extreme spreads and low SD figures. The worst performing CX lot averaged 1.954” over 20 ten-shot groups. Its ES was over 80 fps.

I found that CX and Midas lots that I shot had results that could usually be predicted after gathering chronograph data.
 
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Surprisingly, while the SK Rifle Match was expected to perform less well than best Center X, and all SKRM lots did, what was much harder to anticipate were the results from one particular lot of SK Rifle Match.

I shot 16 targets with four ten-shot groups using five different lots of SK Rifle Match. The ES for the lots shot over the chronograph were high.

Even the obviously best shooting lot of SKRM (SKRM 474) had an average ES of 57 fps and it produced a respectable 28 ten-shot group average of 1.260” – albeit with considerable variation in size from one group to the next. The seven targets averaged between 1.180 and 1.320”.

The other lots were disappointing by comparison.

Nevertheless, that wasn’t surprise. While I have tested only a small number of lots of SKRM, it can be expected to have wide extreme spreads and to have results that reflect that.

What wasn’t expected was how some of the SKRM 474 seemed to defy how the ballistics suggest it ought to behave.

See the groups on the target below which was produced by this ammo.

Considering group ES, the two groups on the left side are as expected but those on the right seem to defy explanation. The smallest group on the target had the highest group velocity spread. An ES of 51 fps in one group ought to have more vertical dispersion. (Yes, I checked it at the time it was shot because the results were so weird.)




This is not a one time thing. It's not the only example of something similar.

See the group on the top right on the target below. It measures .696” CTC (which for SKRM is unusual for its small size) with an incredibly small vertical dispersion of only 0.416” – despite having a group ES of 984 fps – 1030 fps, or 46 fps. A ballistics calculator suggests that a 40 fps difference between fastest and slowest rounds should result in about 1.5” of vertical.



That unusually small group with SKRM is a bit strange. It's even all the weirder because it has an ES almost identical to the group to its left. I'm not sure how to explain that group.

I observed that while faster rounds tended to have a POI higher on the target than slower ones. I saw several examples in which this wasn’t always the case.

Here’s one more example with SKRM of a round not going where its MV in relation to the others in the group are going. The ten-shot ES was a remarkable 18 fps, from 1011 fps to 1029 fps. The MV of the one shot that didn’t go where the other nine did was 1024 fps. Sometimes bullets seem to have a mind of their own, but the errant POI can’t be unexpected with SKRM ammo.

 
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The wind causes horizontal spread or dispersion. This is not a big problem if the wind is very steady. But when shooting in winds that change speed or direction, the effect can be unpredictable.

But is wind the only cause of horizontal spread? No, it’s not the only or even main cause.

Except for the odd time when one of the three wind flags I was using briefly and slightly fluttered, during which time I paused, I shot with as close to no wind as I can imagine. The leaves on the trembling aspens didn't quiver and the lake right by the club property and shooting range maintained a calm, smooth, and glassy surface.

In the mornings when I arrived around 8:30 the lake looked like the image on the left. When I left at near 1:00 in the afternoon on Thursday, the 7th, by which time it had warmed up, the lake showed little change as seen in the image on the right. By that time I had finished shooting almost an hour earlier.




Despite the absence of wind, however, there can still be considerable horizontal dispersion, as the examples below show.





Some groups have more horizonal spread than vertical. None of this can be attributed to wind. It just wasn't there.

One of the things that struck me on these windless days is that with some lots of ammo there is more likelihood of unexpected horizontal dispersion than with others.

What causes this? It's not the wind -- at least not when I shot these targets.

When ammo behaved in unexpected ways, it seems to have happened more often with SKRM than with CX or M+. Why?

Why do faster and slower rounds sometimes not go where the ballistics suggests they ought to go? Why can some ammo occasionally defy the logic of large velocity spread to nevertheless shoot a small group? Why do some rounds have a POI to the left or right of where they’re supposed to go?

Tentative answers can include concentricity issues with the bullet, how it's seated in the casing. There may be defects, particularly in the heel of the bullet that cause it to go where it isn't expected. The bullet's center of gravity may be not be true. This can cause its flight to be unusual.

I don't know the reasons why ammo sometimes behaves in unexpected ways. I thought it was strange to see the range of ammo behaviour, and while the chronograph offered some data to explain much of the ammo performance, it didn't explain it all.

Sometimes .22LR ammo does things that are hard to explain or understand -- sometimes it is strange. It's no wonder that shooters, myself included, can get frustrated. An ammo that gives good results one day may be like a stranger the next. But that's all part of the mystery of .22 rimfire.
 
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Awesome series G! I read everything, and will re-read again and maybe formulate some comments.
That chrono info is both interesting and scary - scary to know there is that much variation within one lot!
 
Thanks for the kind words, gentlemen.

oldstarfire said:
Any thoughts about the "rim thickness" question?
Click to expand...

I won't say much about it except to say that I've never read of any serious shooters who use "good" ammo -- that is, ammo like the better grades of Lapua, Eley, and RWS -- who say they sort .22LR ammo by rim thickness. This sorting method had become popular among some serious shooters for a short period of time (the bandwagon effect, I suppose) more than a decade ago, perhaps longer. But its failure to show real improvement led to its abandonment.

Sorting by rim thickness may improve some inexpensive or bulk ammo's performance, but the verdict is far from clear. If a shooter wishes better results, he should get the most appropriate ammo for his rifle.

Few serious shooters mechanically sort their ammo in any way. This includes sorting by rim thickness, weight, or base-to-ogive length, the latter being the only sorting method I've read about which continues to get some attention. I tried it but could see no improvement.
 
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A feature on the road to rimfire accuracy is that many shooter will be frustrated by unexpected behaviour of .22LR ammo. In an effort to improve results with the often-mercurial .22LR round, many shooters will grasp at anything that purports to offer better results. As far more experienced and much more serious shooters remind those of us who are less seasoned, there are no shortcuts to improving results. If a shooter wishes serious results, he must test for the best ammo. There is no other way.

The results shown in this thread hints that less expensive varieties of ammo may be more capricious -- more fickle and inconsistent -- than better varieties of ammo. They can produce good results on occasion, but they produce many more less-than-stellar groups. In other words, less expensive varieties may put rounds where they are unexpected more often than more expensive varieties.

One big step in the right direction is using ammo that should be of better quality. Of course, not all such ammo is in fact "good" as is shown by the results on target and over the chronograph of Center X lot CX 777. It's worth pointing out that even this disappointing lot usually put its rounds where the MV suggested they ought to be. The problem tended to be vertical spread because of the ES of the ammo in the group. That may mean that even though the MV spread was large, there were fewer other problems with the ammo to cause rounds to have unnecessarily large horizontal spread.




As unacceptably poor as that lot is (CX 777), it's not simply a one-off "mistake" by the ammo maker. Two years ago, I bought a case of CX that shot so poorly it was a struggle to get MOA-or-better groups at 50 (that's 1/2") using several good rifles. (I believe that lot's last three digits were 881.) Fortunately the dealer took that very poorly shooting CX back without any questions.

Having experience with two very poorly performing lots of Center X makes me wonder what percentage of Center X is similar. I'm not suggesting that Lapua ammos are more inconsistent than those made by Eley or RWS. They make poorly shooting lots also.

My experience is primarily with Lapua. I'm wondering if Canada gets more than its fair share of inconsistent match ammo. If poorly shooting lots of CX are relatively rare, is it possible that more of them tend to go to smaller, "less demanding" markets like Canada's, where there are fewer serious shooters? There's far more club-level and higher .22LR competition in countries such as the U.S. than in Canada. Lapua has testing facilities there, too.

It's not that I see a conspiracy against small markets, but they aren't in a position of leverage. Countries where .22LR shooting is far more important than it is here may have reason to expect better lots just as ammo makers would have reason to send them. After all, after decades of experience, the ammo makers must have a very good idea before any testing which lots are likely to be better than average and which are likely to be worse.

Of course, in the end this is simply speculation. Only the ammo makers know, and they reveal few if any secrets.
 
Great information.
Even CCI MiniMags will look good when there is a 4 fps variation and three shots were touching at 100 yards. Shots 4 and 5 were lower corresponding to the lower velocities and ended up 1.75" for 5-shots.
When three consecutive lots from Eley were TEAM, MATCH and TENEX arrived in Canada it is hard to say Canada was getting selected poorly performing ammunition.
Doing rim thickness sorting of MATCH and TENEX was a waste of time as there was less that 0.001" variation.
A lot of TEAM was sorted in to two groups when the variation was greater than 0.001". That made it better practice ammo but not competition grade.
It was also acceptable fouling ammo since the same lubricant is used in those grades.
Since we shoot all year, I have recently been testing TENEX and MATCH Biathlon but Eley says the lubricant is "specially formulated".
The lot numbers I have show that they were produced on production lines 2, 4 and 5. Time to pull and weigh the powders to see if there is anything significant versus MATCH.

On the lighter side, a friend borrowed my Cooper JSR for our Championship 1200 Match. He bought Eley MATCH Biathlon 1085 fps and beat me.

Glenn's testing is significant and everyone should appreciate his efforts.

Weights of powders:
TENEX Biathlon 1091 fps 1.16 gr.
TENEX Biathlon 1053 fps 1.16 gr.
MATCH Biathlon 1085 fps 1.04 gr.
Remington Eley MATCH 1062 fps. 1.08 gr.

I could not see any difference even with a 10X loop.
 
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