Rimfire Ammo Testing Protocols

[Bangarang]

Late summer I picked up a limited selection of several grades of the most favored brands of match ammo discussed in the mega T1X thread. This was in anticipation of testing a new rifle. For various reasons I didn't get the rig assembled until mid-November. Of course quality .22 LR has pretty much dried up since then.

I was wondering what type of ammo testing protocols some of you experienced rimfire shooters follow for testing ammo for a new .22 LR? In particular how to narrow things down when you don't have an abundance of ammo put by.

Also, what's the routine during testing for cleaning and fouling shots when switching between brands and grades?

I have two starting premises: Shoot 300 to 500 rounds of lower budget ammo & while cleaning at regular intervals before embarking on the testing quest, and don't waste any more time with Norma TAC-22! My Tikka hates this stuff!

 

[justin amateur]

Before doing any testing, do some entertainment shooting.
Spend some time plinking, pinging steel, while you go though at least 2 bricks of cheap 22lr.
Clean often. Roughly 250 shot intervals.

Y'er Tikka has no likes or dislikes. It's an inanimate object.
Results on target aren't due to rifle preference, but cartridge quality,
shooter ability, wind and how well the rifle was manufactured.
Get a good box of Norma, you'll be bragging, get one with assembly line defects, you'll be annoyed.
Cartridge quality is not a constant, it varies minute by minute on the assembly line.
Find a good batch, get great results.
Get a box that was mishandled, dropped, assembly tolerances slipped, you get strays and fliers.

Test off a solid bench, from a one piece rest, over a chronograph,
indoors or in a location with no wind.
Ensure the barrel and receiver are securely fit to the stock.
No rocking or movement relative to the inletting.
Support the rifle at the rear and just forward of the barrel receiver joint.
Not out at the sling stud, to avoid stock flex or springboard effect.

Run at least 100 rounds to verify the results.

5 shots is a random act of accuracy.
10 shots is a wallet group.
30 shots is a good start.
50 is the minimum needed to make a decent guess.
100 is enough to draw a useful conclusion.

The Eley lot analyzer offered these comments

 

[rick137]

Before doing any testing, do some entertainment shooting.
Spend some time plinking, pinging steel, while you go though at least 2 bricks of cheap 22lr.
Clean often. Roughly 250 shot intervals.

Y'er Tikka has no likes or dislikes. It's an inanimate object.
Results on target aren't due to rifle preference, but cartridge quality,
shooter ability, wind and how well the rifle was manufactured.
Get a good box of Norma, you'll be bragging, get one with assembly line defects, you'll be annoyed.
Cartridge quality is not a constant, it varies minute by minute on the assembly line.
Find a good batch, get great results.
Get a box that was mishandled, dropped, assembly tolerances slipped, you get strays and fliers.

Test off a solid bench, from a one piece rest, over a chronograph,
indoors or in a location with no wind.
Ensure the barrel and receiver are securely fit to the stock.
No rocking or movement relative to the inletting.
Support the rifle at the rear and just forward of the barrel receiver joint.
Not out at the sling stud, to avoid stock flex or springboard effect.

Run at least 100 rounds to verify the results.

5 shots is a random act of accuracy.
10 shots is a wallet group.
30 shots is a good start.
50 is the minimum needed to make a decent guess.
100 is enough to draw a useful conclusion.

The Eley lot analyzer offered these comments

View attachment 7508734

@justin amateur:

Seasons Greetings.

Struck me that in the Eley 50 shot test none of the rifle or barreled action, ammo and support combos had close to sub 1 MOA accuracy at 50m. What does that say?

Question of the day. Your statements imply need 1000 shots to season/break-in a barrel. Do you have experimental verification of that statement or a reason(s)? Seems excessive except perhaps for the leade and the initial part of the bore. I ask because posts have stated Lapua suggests 1000 shots before sending the barreled action plus trigger to me for testing. Something I want to do with my next rifle.

Rick

 

[justin amateur]

Tim says I'm wrong, but that's okay.

Every shot causes wear to the bore. It's microscopic and incremental.
Lead styphanate contains powdered silica, the frictive agent that ignites the primer.
The primer residue gets blown into the bore with each shot fired.
Silica is an abrasive, harder than steel on the MOH scale.
Every following shot carries that miniscule amount down the bore, polishing the rifling.
It is fire lapping the rifling with every squeeze of the trigger.
Smoothing out small burrs and filling microfissures left from the hammer forging process.

I've read the factory ammo test centers also recommend 1000 rounds sent before using the test facility.


Rick, someday I'm going to spring for a quality borescope and a cheap 22 rifle, maybe a cricket.
Then record images of the bore at fixed intervals and locations from chamber to muzzle.
First images fresh from the factory.
Then after cleaning before use.
Then at 100 shot intervals for a full case of cheap 22lr.
See if what I believe is true, or if Tim is right.

With an image record over time, there will be documented proof, one way or another.

 

[RTH1800]

It only takes 3 shots to determine inherent accuracy. One at 25 one at 50 and one at 100 yards.

 

[justin amateur]

Not if I'm shooting offhand RT.
Then it's just proof of my basic lack of skill and talent.


Did you finish dusting y'er stash?

 

[RTH1800]

My work is never done!

 

[RTH1800]

OP,

Sorry to get off track on your thread.
Justin’s recommendations are valid.

If, like most of us, you are not driven to his level look at the 6x5 thread.

A reasonable amount of information can be derived from shooting six 5 shot groups on a single target.

Good Luck!

 

[Bangarang]

Thank you all for the advice. I was planning on plinking and cleaning, plinking and cleaning ... before starting into accuracy testing.

 

[JimTN]

I would suggest cleaning, or at least running a couple wet & dry patches thru the bore when changing brands of ammo due to the different lube used by different companies.

 

[justin amateur]

Jim, just because it's a slow day at the office...

I've tried cleaning between brands and then testing, also not cleaning and testing.
In both cases it takes 10 to 20 shots for my groups to tighten up.
I assume it's due to the difference in lubricant from brand to brand.
Either method works but I'm lazy so I don't clean between brands.

 

[RTH1800]

As Justin says above. It's more fun to shoot than clean and less risk of accidental bore damage from an errant rod.

 

[Tim7139]

Tim says I'm wrong, but that's okay.

Every shot causes wear to the bore. It's microscopic and incremental.
Lead styphanate contains powdered silica, the frictive agent that ignites the primer.
The primer residue gets blown into the bore with each shot fired.
Silica is an abrasive, harder than steel on the MOH scale.
Every following shot carries that miniscule amount down the bore, polishing the rifling.
It is fire lapping the rifling with every squeeze of the trigger.
Smoothing out small burrs and filling microfissures left from the hammer forging process.

I've read the factory ammo test centers also recommend 1000 rounds sent before using the test facility.


Rick, someday I'm going to spring for a quality borescope and a cheap 22 rifle, maybe a cricket.
Then record images of the bore at fixed intervals and locations from chamber to muzzle.
First images fresh from the factory.
Then after cleaning before use.
Then at 100 shot intervals for a full case of cheap 22lr.
See if what I believe is true, or if Tim is right.

With an image record over time, there will be documented proof, one way or another.

whoa there sharpshooter, Tim has said you’re wrong about many areas, lets try and concentrate one or two since you are conflating several things....,go figure.

First off, to be accurate, priming silica ( glass, essentially) used now has changed materially from just a couple years back, in regards to ELEY anyways.
a couple years back, they used a much bigger medium which was getting ironed into match barrels, at least the first few inches, mostly @ 6 o’clock andwas eroding bores at an accelerated rate.....it was alarming, in particular in barrels using softer variations of 416 steels but even with 416R’s very noticable.

Now, today, much smaller particulate seems the norm, adequate ignition but mostly carried out the muzzle imbedded in warm lube, it largely does not polish the bore, shitty cleaning practices do more in that regard..
obviously, every combustion event does SOMETHING at a molecular level, I have never said otherwise.
Lastly, mostly, testing centers, want some rounds down the bore to “season “ somewhat, your chamber/ throat in regards to how quickly they build up carbon and/or lead fouling, which will absolutely impact. performance so with your previous recommendations about throwing 200-300 rounds through these things as a first, at least regarding a high grade/ match barrel......you are already into the weeds. I can guarantee you, how you start out with a high grade barrel will have impact as to your likelyhood of extracting everything that chambered barrel can yield in it’s lifetime.

 

[justin amateur]

Tim...Merry Christmas.

What do you think I will see with a borescope and new barrel
if images are recorded at 100 shot intervals?

Improvement to the bore finish over time, deterioration, or no change?

I don't mind being told I'm wrong.

The explanations why provide useful information.


Checked and the price on a decent USB 5 mm borescope with solid shaft
is now less than 100 bucks including shipping.
I can purchase an extra 22lr barrel from CZ for about 150 bucks.
I've finished with the 50 at 200 yards, need a new hobby.
Find out if rimfire barrel break-in is an internet fable or truth.
Good thing I'm easily entertained.

 

[Criver600]

First off, to be accurate, priming silica ( glass, essentially) used now has changed materially from just a couple years back, in regards to ELEY anyways.
a couple years back, they used a much bigger medium which was getting ironed into match barrels, at least the first few inches, mostly @ 6 o’clock andwas eroding bores at an accelerated rate.....it was alarming, in particular in barrels using softer variations of 416 steels but even with 416R’s very noticable.

Back in the day if shooting Ely exclusively, you could expect a depression eroded right in front of the chamber, match barrel life was 40,000 rounds.

 

[Tim7139]

Tim...Merry Christmas.

What do you think I will see with a borescope and new barrel
if images are recorded at 100 shot intervals?

Improvement to the bore finish over time, deterioration, or no change?

I don't mind being told I'm wrong.

The explanations why provide useful information.


Checked and the price on a decent USB 5 mm borescope with solid shaft
is now less than 100 bucks including shipping.
I can purchase an extra 22lr barrel from CZ for about 150 bucks.
I've finished with the 50 at 200 yards, need a new hobby.
Find out if rimfire barrel break-in is an internet fable or truth.
Good thing I'm easily entertained.

Thank you, and same to you.
Well your question is easy to answer but, how valid I don’t know.
You will see fouling, you will see carbon, maybe lead in the throat.
A fair consideration for a new barrel, is how you season that chamber, how fast does fouling build, exactly where.
Now remember, this applies to the benchrest world so the farther away from that you are, the more you’re milage will vary.
It is a well known fact that the slower your throat ( talking true match chambers here) takes to foul, the longer your rig maintains top accuracy, most precision shooters clean after every target, or when starting out, usually after a box. It makes a difference. I read, lots of guys shooting all manner of lower&mid priced ammo and I doubt anything here is valid under those circumstances. Plent of guys cannot justify dropping $15/box for rimfire
Now shooting 50 @100 yds., hitting a plate at distance.... Neither I nor anybody else can probably exactly quantify that but I go under the assumption, you pay hard earned $ for equipment, is there a downside trying to extract the best from it?

 

[Tim7139]

Back in the day if shooting Ely exclusively, you could expect a depression eroded right in front of the chamber, match barrel life was 40,000 rounds.

Well, the stuff I referred to not that long ago......certain barrels were toast after a couple cases of ammo. You checked with a borescope and saw monster pits.... edges of the lands missing.

 

[JimTN]

10-20 rds before it settles in, can't say that I blame you much. I'm used to 5 rds with the last 3 stacking on top of each other.

 

[rick137]

Perhaps a benchrest shooter would describe the procedures they use for testing/selecting ammunition.

My hypothesis is using the results from a 6x5 Challenge or 50 shots at 100yd to select type-lot of ammunition is suspect. As @justin amateur stated "Cartridge quality is not a constant, it varies minute by minute on the assembly line." At some level this must be true since all manufacturing processes have finite tolerances.

The first question one might is what are these manufacturing tolerances and what is the statistical procedure/analysis for determining them? However, I presume that information is proprietary. The second question is how big are lots? Hundreds of thousands of rounds? Millions of rounds? The third is how does the quality change from the first round to the last round in the lot? Linearly, i.e. getting better or worse from first to last? More or less sinusoidally, i.e. quality increasing and decreasing during the manufacturing process? Or some more complicated function? The fourth is what is the range of quality variation in terms of accuracy/precision, 0.001 MOA, 0.01MOA, 0.100 MOA? This question is truly hypothetical because ammunition does not have an accuracy/precision. Only a rifle, shooter and ammunition have an accuracy/precision at a certain distance in certain environmental conditions. So all components other than the ammunition would have to be either the same or the differences insignificant compared to the difference caused by the ammunition for the comparison to be valid.

Another hypothesis is the intralot variation in quality could well be greater than the interlot variation in quality. How many rounds of a lot would it take to make a proper statistical determination of interlot variability? How many rounds of a lot would it take to make a proper statistical determination of intralot variability? Perhaps 100 is sufficient, perhaps not. If we knew the manufacturing tolerances could have the information to say statistically. But we don't.

People send their barrel actions plus trigger to a test center for determining the “best” ammunition. From each type/lot there are 10 or 20 shots? Is ten or twenty shots sufficient to sample the “accuracy of a case”? Perhaps better than nothing, perhaps not in sense results are a chimera. Perhaps the real effect is to give the shooter a warm and fuzzy feeling. Or in these days and times a place to buy ammunition.

Possible amusing scenario. Send a barreled action plus trigger to testing center for testing with three different types/lots of ammunition. Could be three lots of same type or one lot from three different types. Doesn't matter. Label them ammo1, ammo2 and ammo3. Now for first test choose a box of three different ammos. Result could be accuracy of ammo1>accuracy of ammo2>accuracy3. Choose three different boxes of ammo. Could be for those boxes the accuracy order is ammo2>ammo3>ammo1. Six different permutations possible. What is probability all six occur?

Same comments apply to using a 6x5 Challenge average results. Sadly the standard deviation for each type/lot of ammunition is not calculated to determine the amount of overlap between results for different ammunition. Also sadly in sense much more information to be gained from little more effort is not shooting a 10x5 Challenge. From a 10x5 Challenge there are many ways to form 6x5 Challenges from the individual 5 shot groups and then powerful statistical tests can be brought to bear.

To one and all good luck in selecting ammunition.

 

[justin amateur]

Lot quantities vary...look at the Eley lot analyzer pic above...5-1/2 cases in that one. 28,485 loaded in that run.

 

[rick137]

Some interesting comments on Eley Lot Analyzer on Rimfire Central. In the example you posted, assuming barrels made little difference, there are 200 samples from a population of 28, 485. One round out of 142 sampled. What is that worth? Would be nice to know if every 142 round manufactured was sampled.

Further comment. Nothing so far posted in this thread provides data to substantiate requirement to fire 1000 rounds before ammunition testing. Thus to each is own protocol and may the most optimal win.

 

[Tim7139]

First off, I think Lapua has a 200 round count requirement, that said, if you're going to test it should be with a rifle tuned and frankly that takes some rounds.
Secondly, it is fallacy to assume best grouping guns always shoot best scores.
ELEY is an amalgamation of multiple 10 shot groups but myself, I look as much at other stuff.
I will pass up outright smallest group for nice round ones without outlyers around the edge and when that site comes back, hopefully, you want to look at the other data, as in the % of shots falling within 10 ring.....anything in the mid 90% range( rare) is some good stuff.
you have to factor in that ELEY uses 4 barrels, none of which are likely as good, or chambered as well as a first rate BR type smith is going to fit, so you have to realize, buying using only the analyzer required a theirs to mine type translation.

Most guys, most times, simply buy lots and shoot targets or group buy, group test under the assumption lots of ammo will shoot in somebodies gun.....a lot of ammo , ho hum in yours may be great in mine.....it can be VERY barrel specific.
I’m like a lot of guys, my barrels are not super fussy, if it’s good, it shoots in them.

 

[grauhanen]

Struck me that in the Eley 50 shot test none of the rifle or barreled action, ammo and support combos had close to sub 1 MOA accuracy at 50m. What does that say?

With this lot of ammo, less than six cases were made, which suggests it's one of the better varieties of Eley. Only two of the 20 ten shot groups had outside-to-outside sizes under .50", with another eight between .50 and .60" (oto). Eight of the ten shot groups were between .60" and .70" and the remaining two were over .70".

Of the four 50 shot groups, three were between .69" and .75" -- all fairly close -- and the fourth was .85". The average is .75". None were sub 1 MOA. Is that unusual?

Below are 50 shot groups from five random lots of Tenex that were made in 2018. The average of each is .72", .91", .77", .78", and .80" from top to bottom. None of them is significantly worse or better than the sample given by justin amateur.

As noted above, there are a lot of factors that go into making ammo that is among the most consistent available. Obviously there are many variables in the ammo components and/or the manufacturing process that can't be sufficiently well controlled to make ammo much more consistent than it is currently. When one lot of ammo is more consistent than another in a rifle, that is cause for appreciation because a lot of hard-to-control things went together successfully. Locating those lots is always a challenge. And to complicate things, because no two bores are the same, a lot that shoots well in one rifle may not shoot well in another -- something the Eley Analyser results below illustrate.

Ammo inconsistency explains why the group sizes are what they are. In every box of ammo there are 50 rounds with the potential to be different from one another. Many of them may perform almost identically, but few if will be exactly alike. Think of all of them like flyers -- with some rounds noticeably worse than others.

It's doubtful that a borescope examination of the condition of a bore over the course of thousands of rounds will be able to reveal significant changes. Deterioration may be hard to detect with a borescope. In any case, a borescope may not be the best instrument to use to determine the ways in which a bore may change over the life of a barrel.