Weirdness with Lot-Tested Center-X

DownhillFromHere · Nov 5, 2024

Summary:

Had my 1st-gen Vudoo tested at Lapua's AZ test center early 2020. Bought 2 cases Center-X. I'm down to three (3) bricks of it.
Over thousands of rounds, this ammo has averaged ~1080fps with an SD ~7-9, depending on temperature.
Accuracy is a consistent 1.0 - 1.1 MOA @100, with plenty of 1/2-3/4" groups to be had.
Then, last month at a monthly gallery-style match, I missed four 100-yard targets. Perspective: to that point, over the last three seasons and 18 matches, I missed a total of 7 100-yard targets.
I thought my scope (ZCO 527) had crapped the bed... Yesterday I learned otherwise: Every round chronographed in one box of this ammo was 50-70fps slower than the historical average. JUST THE ONE BOX.
Ammo has been stored in benign HVAC-controlled environment, temp 65-75 F. / humidity 45-55%. Definitely no solvents, WD-40, etc. stored in the same room or even in the same wing of the building.

So today I took the remaining 20 rounds from that "bad" box to the range along with the remaining seven boxes in the brick (two boxes fired at the disastrous match). I tested 5-10 rounds out of each box. None of the rounds tested from the "unknown" seven boxes chrono'ed low; in fact, four box's samples tested about 10-15fps high. After each "unknown" sample, I fired a couple of rounds from the "bad" box - all of which were 50-60fps slower than historical average.

Lessons learned:

Before using the remainder of this lot-tested Center-X in competition, I will test five random rounds from each box.
In fact, from now on, I'll sample a few rounds from every box from every lot I ever buy again before competing with them.
I'll only buy one case after the next test session. Given the "profile" of how these weird rounds presented, I doubt that the ammo's age is the cause of these two boxes (from the same brick) having such low velocity. (Note: I shoot a lot of SK ammo to save the lot-tested stuff.)

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Anybody else ever experience anything like this? I've seen some puzzling things in six decades of shooting, and this one is brand-new!

Defender32 · Nov 6, 2024

This is the RimFire Lottery. Even though its lot tested it does not mean every box will be the same. If you had gotten 2 rounds of the bad 50 spread across 25 bricks it would have never crossed your mind. It's just a random thing it happened in 1 box.

doing what you say of pulling random shells from each remaining box in bricks and testing is all good and within reason. Just check it morning of your matches.

Id say you are lucky to have 2 cases last 4 years. I'll shoot almost 2 cases a year.

DownhillFromHere · Nov 6, 2024

Defender32 said:
This is the RimFire Lottery. Even though its lot tested it does not mean every box will be the same.

I'm well aware of the rimfire lottery... there has been "a lot of lots" of other ammo down the tubes (Vudoo, Rim-X) besides the Center-X. As well as my C-X lot shoots, there have been the random rounds that drop a few tenths low at extended ranges (>150 yards).

I'm still finding it hard to believe that I have an entire box, plus at least part of another box, from the same brick (out of 20 bricks purchased) that are so consistently slow. And when I say "consistently" - I'm talking similar ES/SD numbers to the rest of the lot, just 60fps slower. IN ONE BOX.

With that said... over the last four years shooting that little gallery-style match, the season points races have come down to the same handful of shooters running Vudoos and one guy with an Anschutz. The smallest targets on the 150-yard racks are just over 2 inches wide, situated in a corner of a square range with berms immediately behind and beside. Wind swirls around those berms, which are covered with brush (essentially no splash). Only one of those guys runs SK ammo; I run C-X, another ran Midas+ but has moved to Lapua Long Range. The Anschutz guy runs nothing but X-Act. We're all within a target or two of each other on any given match day. The high-dollar labels aren't doing notably better than the mid-range stuff.

justin amateur · Nov 6, 2024

I hear y'er complaint Downhill.

It ain't news to me.

I've had issues with supposedly match quality cartridges from RWS, Lapua, Eley and Fiocchi Italia.
Chrony spread in excess of 40 fps for a box of 50. Odd strays that don't fit wind direction/speed.
I was told my rifle didn't like the brand, or I was at fault as high end 22lr doesn't have those issues.

Nope, just less than desirable quality cartridges rolling off the assembly line.
Or cartridges that had shipping/handling problems before delivery.
Statistical sampling at the factory doesn't catch all the problem cartridges.
The factory has acceptable defect rates per 100,000 units and a sampling confidence level
that allows lesser quality cartridges to end up in consumer hands.

Remember the problems with Eley's recent long range 22lr?

Lastsaint21 · Nov 7, 2024

I mean this in the kindest way.. Nothing with Fiocchi Italia on it should ever be mistaken as match ammo in 22 rf.

justin amateur · Nov 7, 2024

I hear ya' Saint.
I picked up a few of bricks of the Official 300, 320 and biathlon.
At 200 yards they produced 50 shot groups that equalled the best results
from Eley, RWS and Lapua/SK.
Also had boxes that doubled the spread.

Some times I luck out with assembly line lottery.
Sometimes I don't.

VFL1911 · Nov 7, 2024

Feels like a stupid question, but I have to ask…you did clean your barrel right? Or at least maintain your usual routine?

I tend to always start there when seeing fluctuations with same lot and people often forget to clean.

chevy_man · Nov 14, 2024

Lastsaint21 said:
I mean this in the kindest way.. Nothing with Fiocchi Italia on it should ever be mistaken as match ammo in 22 rf.

I had really good luck with the 300, but I just grabbed a case because the lgs had it cheap enough.
As far as I know there's nowhere to get it lot tested, but I'd put it with SK quality wise.

If it's center-x pricing I'd definitely pass though.

Lastsaint21 · Nov 14, 2024

chevy_man said:
I had really good luck with the 300, but I just grabbed a case because the lgs had it cheap enough.
As far as I know there's nowhere to get it lot tested, but I'd put it with SK quality wise.

If it's center-x pricing I'd definitely pass though.

As long as you know what your buying.. meaning you dont expect great results. You might get them, rimfire is an odd thing..there is a 1 percent chance of anything it seems..

mark5pt56 · Saturday at 8:13 AM

Indeed, just shot a Veterans Day match, 100 yards, I have been practicing, getting used to the wind, etc, pulling 300/20-28x for multiple sessions. Well, here I am onto the second target with a 100/6x on the first one(wind was whipping right to left 10-15) Holding a wee bit high and low, 1-2 moa right depending and guess what? I watch the bullet fly high and right into the 8 ring! Two things-my hold would no way put me there and the bipod, rear brick bag would not allow that much movement. This was the last box out of a brick, all same lot etc. of course.(CX) It happens and other than visual inspection, no way to know which one of those will do it. I've been tracking every shot from this lot with the Garmin, SD on each session, 40-60 rounds, 7.5-10. Any high or low velocity does show on the target and referenced, those will still be in the fringes of the 10 or barely into the 9. For the .22, I really like the Garmin as a tool to help explain where the shots go and to show my cleaning method does not produce CCB variations.
My buddy who was 3rd with 300/28x had it happen to him on a previous match with Midas-one round grew wings.

DownhillFromHere · Saturday at 9:34 AM

It's one thing to have the occasional flyer. That's .22LR. What was so weird here is that it was an entire box plus 15-20 rounds out of the adjacent box in the brick (out of 20 same-lot bricks ordered) that were ALL 50ish fps slow.

Never heard of that before. I don't know much about how rounds come off machines and get packaged, but there certainly seems to have been a momentary hiccup in the process...

justin amateur · Saturday at 10:51 AM

Factory batch testing from Lapua, RWS and Eley
is based on statistical sampling by test firing from fixtured barrel/receivers.
4 to 5 test rigs are used in a tunnel, and cartridges selected from a batch
are fired from the 4, or 5, barrels and the results documented.
Sample amounts fired are based on the desired level of confidence
from the total number of cartridges in that batch.
If all 4, or 5, barrels show results within specified parameters, that is labeled best.
Next level lower results, based on factory specifications,
is boxed as a lesser priced target ammunition.
Third rated cartridges get labeled as practice ammo at a substantial cost cut.
All from the same machines and supply chain,
but with variations in chemistry, assembly and tolerances.

Management establishes acceptable defect rates per 100,000 units
and the level of confidence used to determine sample size.
An 80% level of confidence, translates to 8 out of 10 times the test is run
you will obtain similar results. 2 out of 10 you won't.
So from a batch of 10,000 cartridges, all might be similar,
or 20% could be substandard, due to the sample size actually tested at the factory.

Profit is the primary focus.
Quality control exists to instill consumer confidence,
in order to maintain and increase sales.
When substandard cartridges slip past quality control,
contact customer service and notify them they have a problem.
Enough complaints and a related drop in sales,
will cause a change in manufacture.
Failure to complain and continued rate of sales,
don't expect any changes in the manufacturing process.

Where did my information come from?
I contacted RWS, Lapua, Eley and asked questions.
Normal customer service had to contact the factory
in order to obtain answers to my queries.

Sample sizes, confidence levels, acceptable defect rates
and accuracy parameters are considered proprietary information.
No information released on those numbers.

So crap cartridges can get past factory batch testing.
Label does not guarantee results. Simply improves our chances
of obtaining cartridges capable of meeting our expectations.
Quality is job 2. Profits are job 1.

grauhanen · Saturday at 1:04 PM

justin amateur said:
Factory batch testing from Lapua, RWS and Eley
is based on statistical sampling by test firing from fixtured barrel/receivers.
4 to 5 test rigs are used in a tunnel, and cartridges selected from a batch
are fired from the 4, or 5, barrels and the results documented.
Sample amounts fired are based on the desired level of confidence
from the total number of cartridges in that batch.
If all 4, or 5, barrels show results within specified parameters, that is labeled best.
Next level lower results, based on factory specifications,
is boxed as a lesser priced target ammunition.
Third rated cartridges get labeled as practice ammo at a substantial cost cut.
All from the same machines and supply chain,
but with variations in chemistry, assembly and tolerances.

This is an explanation the match ammo makers would endorse. There's no way to know, however, if the ammo makers have revealed the full explanation of how testing is done, when it's done, how often it's done -- or much of anything else. It's all proprietary -- secrets that are never publicly revealed or discussed.

Do ammo makers test each lot and only then decide how to label it? If they did, it should be statistically unlikely to get a bad lot of X-Act or Midas (or some other top tier variety of match ammo). Otherwise, why else do such testing?

Is it realistic to think that the ammo makers compare the results of testing with different test barrels and then only if they are within certain parameters label that ammo as best? While it's likely that such comparisons can now be achieved by electronic means without humans looking at targets, in the past this was not yet possible.

Nevertheless, in the past great quantities of ammo were somehow regularly labeled or graded. Was it done by people comparing test targets and saying something like "Hmm... this could be best rather than second best"?

Perhaps not. Perhaps ammo was graded or labeled by other means which may have included some actual testing of certain quantities in one or more barrels.

______________________________

Eley, if not the other match ammo makers, has revealed that the components themselves are graded. The brass casings, bullets, propellant, priming compound is evaluated and subdivided into lots. These are not all the same or equal. Why else grade them?

As speculation, it might make sense for the ammo makers to organize the components so that the best of each come together in the loading machines at the same time. This way the best casings, bullets, propellant, and priming compound are put together in the same finished rounds.

Further, if the loading machines tend to operate best at a particular time or point in production, this too could be used to advantage when the best product is desired.

The output of these efforts could then be labeled "best" without testing any of it in test barrels. The next best components would be put together to become the next best variety. Of course in the real world such processes don't always work out as planned and desired. The result, for example, would be lots of X-Act that are outperformed by Midas or Midas that's outperformed by Center X.

mark5pt56 · Saturday at 2:34 PM

DownhillFromHere said:
It's one thing to have the occasional flyer. That's .22LR. What was so weird here is that it was an entire box plus 15-20 rounds out of the adjacent box in the brick (out of 20 same-lot bricks ordered) that were ALL 50ish fps slow.

Never heard of that before. I don't know much about how rounds come off machines and get packaged, but there certainly seems to have been a momentary hiccup in the process...

That would make me think the production line had some type of packaging snafu.

Tiger_Shilone · Saturday at 5:02 PM

DownhillFromHere said:
It's one thing to have the occasional flyer. That's .22LR. What was so weird here is that it was an entire box plus 15-20 rounds out of the adjacent box in the brick (out of 20 same-lot bricks ordered) that were ALL 50ish fps slow.

Never heard of that before. I don't know much about how rounds come off machines and get packaged, but there certainly seems to have been a momentary hiccup in the process...

Yea that would be my guess on it as well. Bad luck to have a box or two that had an issue going on during manufacturing (something like powder level got low before the machine noticed and filled the powder back to normal level?). That could definitely slip past batch testing.

After watching a video of CCI’s factory tour of how 22 ammo is made, I am amazed at how consistent some 22 brands are. Still sucks getting a turd in every box it seems, even in the premium tier grades. When I shot ARA benchrest I normally set up a chrono and logged every round for the match. Extreme high/low FPS spread bullets accounted for a good portion of my crappy shots, but I made my fair share of mistakes too.

LuckyDuck · Saturday at 11:41 PM

50-60fps would certainly make a world of difference. It's rimfire so as you know it could be any number of things. If for nothing else other than my own curiosity, I'd likely wait for the season to end and clean the barrel well (hadn't seen this mentioned but apologies if I missed it) just to see if that made a difference but it might not be worth the effort if you're down to the last 1.5K rounds and are planning to get it lot tested again. Although if that's your plan, maybe it would be worth ruling out a fouled barrel before your next trip to Lapua.

Either way, good luck narrowing down the culprit.

-LD

DownhillFromHere · Sunday at 10:24 AM

LuckyDuck said:
...good luck narrowing down the culprit.

Guys, I'm confident that I just have an unusually weird occurrence in the weird world of .22 rimfire. I found it interesting so I put it out here for others to see.

To reiterate from the original post: after identifying the "bad box" of ammo, I:

Chronoed five-ish rounds from other boxes in the brick, which tested with normal velocity/ES/SD.
Chronoed five-ish rounds from "bad box" - all were 50-ish fps low with similar ES/SD values to normal rounds.
Repeated steps 1 and 2 three times, same results.

Cleaning has nothing to do with it, because I can repeat the velocity differences from "bad box" string to "other box" string.

Finally, I used two boxes from that brick in the final "gallery-style" match of the season last weekend. Cleaned it. In the five years I've enjoyed this little monthly match, I'd only cleaned the 150-yard rack once. Same with the other perennial top scorers; cleaning the 150 rack is relatively uncommon because the smallest five targets are right at the edge of .22LR capability even in perfect conditions (which we enjoyed last weekend).

Bottom line is I've had 50-75 consecutively-packed rounds out of 8500 with a 50fps drop in velocity. [shrug] Another day in rimfire land.

buffalowinter · Sunday at 10:46 AM

Eliminate all variables. Test the ammo in another rifle and see if you get the same results. Clean your rifle, attention to bolt and chamber face.

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