Rim Sorting 22LR: Testing the lore

[MoondogIndustries]

https://youtu.be/T1dh5fs31iI

After testing weight sorted Federal Champion 22LR LRN and finding that they produced 60% smaller groups than non weight-sorted cartridges, I decided to test the other big old-school 22LR accuracy technique: sorting cartridges by rim thickness.

The thickness of the a 22LR rim can effect the amount of headspace of the bullet in the chamber. And presumably, the thickness could also effect the amount and burn rate of the primer inside it.

No spoilers but I do have some additional ammo tests coming. Be sure to SUBSCRIBE to my YouTube channel and you'll be updated when I finish and post it.

[NeilMo]

Very interesting. Have you thought about adding a re-crimp to your ammo for testing? Years ago I used to target shoot with an old-timer who would re-crimp all his bulk 22 ammo. His precision was definitely better than most as I recall.

[SharedShots]

Weighing 22 ammo, measuring rim sizes and so on without approaching it from more than some casual correlation and from that assuming conclusion is the the myth.

Some questions:

1. Which component was responsible for the variation in weighed groups?
2. What is the pattern of weighed groups in relation to lots? Is it repeatable?
3. What is the POA/POI shift between weighed groups and by how much and is that consistent between weighed groups of different lots but that weigh the same?

Without being able to answer those questions and a slew of others, none of this matters nor is it valid information, it's interesting perhaps but proves nothing and conclusions drawn are guesses which have less effect than how much dust is in the air and the temperature when you squeeze the trigger.

More questions:

How many different groups are in the typical box of ammo and does it vary but which lot they came from?

Do weighed groups from different lots but which have similar weight all shoot to the same POI? If not, why not?

These tests have been going on for decades, it's nothing new.

For primer burn rate, measuring rim dimensions assumes that each measurement is made on rims that have the exact same amount of primer and the primer is distributed the same inside the rim in the same thickness. It also assumes that all firearms will have similar results when none will have the same firing pin speed, amount of impact upon the rim and so on. IOW, it's useless.

Was each fired cartridge chambered with the log stamping oriented in the same direction relative to the chamber? If not, then all the tests are invalid. Tests were done decades ago where each cartridge was chambered with the same logo orientation so that the firing pin would always impact on the rim in the same place. Lots of people then started making sure they chambered their rounds the same exact way and there were claims this made some difference. It did, in imagination because none of the other variables were taken into account.

If one wants consistency, take the same effort and resources spend measuring things that don't matter, weighing cartridges that don't matter and find the best grade of ammo, test lots to see what shoots best and buy a bunch of it.

None of these tests prove anything beyond what the tester wants to conclude, there is no testing approach that could be considered valid.

Sorry to burst bubbles but just what is anyone going to do with 22 ammo all segregated according to weight and maybe even rim size except realize that to get enough ammo that shoots to the same POI (since the idea here is accuracy right?) that they'd have to buy so much ammo the price of the bet ammo in the world would seem cheap by comparison.









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[MoondogIndustries]

Perhaps "myth" wasn't the appropriate word to use in the title. I've changed to the word to "lore" so as not to prejudice the reader.

"None of these tests prove anything beyond what the tester wants to conclude, there is no testing approach that could be considered valid"

I strongly disagree with this statement. I honestly did not have any skin in this game. When I tested weight sorting 22LR, people suggested I test rim sorting too. I asked one of the competitive shooters at my club about how to go about that and one lent me his this tool to speed the process.

My video shows the process I took to get the results I got. And for me that's valid for this test. Take everything with a grain of salt. Your milage may vary.