Not wasting further time or money on rimfire sorting by rim thickness!

[berettaprofessor]

This thread got me curious about the importance of rimfire sorting: https://thefiringline.com/forums/showthread.php?t=616506

So I bought one of these: https://www.midwayusa.com/product/1012739732?pid=382448 and while on a COVID quarantine (yes, I've got it even though vaccinated 4 times), I did a little measurement with my analog dial calipers.

I tested an entire 50 round box of CCI Standard 22lr, 10 Federal Champion, 10 Federal Automatch, and 10 Wolf Match and found <0.001 variation within any given ammo group and only <0.0015 variation between all manufacturers. It seems with modern manufacturing, any variation within an ammo lot is going to likely not cause variation and may be below my test precision. Every single round tested fell between 0.405 and 0.420 thousands rim thickness. I also tested 10 rounds of Fiocchi .22 win mag and they were all within 0.001 of the same thickness.


Cartridge weight, however is a different matter. Look at the attached chart of cartridge weights in that 50 round box of CCI:


I think I'm going to set up with a lead sled for a 50 yard test of a few five round groups of that 51.2 grain weight, and then compare group size with a few 5 found groups taken from a mix of the extremes here. Now that one will be interesting!

 

[stagpanther]

Rim thickness is not the only thing that is critical for proper headspacing--so is uniformity of the rim--some may not be perfectly perpendicular to the length of the case body. I found this out the hard way when I bought thousands of pre-primed FedArms 22lr cases (not to be confused with Federal) most of which are useless after I discovered this defect after blowing several case heads off.

The variations in weight--was this measuring complete cartridges? My guess is that much of the variation in weight is likely due to the bullets themselves. The state-of-the-art in 22lr consistency in bullet design right now still is lead bullets with lubrication. I've yet to see a solid or jacketed bullet that can best the best of the lead bullets; my theory is that the transonic barrier is insurmountable given the limitations of the 22lr cartridge. Thankfully, the industry continues to try to breech that barrier. I doubt even the best factory centerfire cartridges are made with the same degree of precision as the better 22lr ammo is.

 

[berettaprofessor]

Yes, Stagpanter, full cartridge weights and yes, I'm betting the majority of the difference is the bullet weight.

I was just surprised to find rim thickness that consistent, given the hype for measuring it.

 

[FrankenMauser]

It would be interesting to see if your groups change if you let that Federal Champion age until the wax swells (40 gr RN 'Target' assumed). For some reason, the 'Champion Target' has issues with wax - at least for me. Give it 5-6 years, and it becomes difficult to chamber. Let it sit for 10 years, and the wax is so swollen that it starts flaking and peeling; and the ammo is only usable in single-shots, revolvers, and manual repeaters with easy access to the chamber.


---

That Fiocchi .22 WMR would also be CCI production, unless it is the old, red-striped, purple cardboard box. Then you'd be looking at Armscor -- which is obvious, because of the 'T' head stamp.
So, you're probably measuring one of the best hulls on the market.
Either way...

In my experience, the Armscor ammo is just as consistent and reliable as CCI.
Both are at the top of my list for hulls. (Federal, Speer, Fiocchi, and Hornady get to tag along, since CCI makes that ammo.)
Winchester Supreme comes in second (rim thickness and diameter are a bit variable).
Then Remington (pre-CCI) and Winchester general production come in much lower. They're not even on the list. They fill out the cesspool that I dropped my pen into.

I do not know what the next incarnation of Remington .22 WMR will be. The last production era had CCI contracted to make it, but I haven't seen any news or product since the bankruptcy.

I have not tried or measured Aguila or Target Sport .22 WMR. I have no idea where they fall. Perhaps at the bottom, for Target Sport, since the WMR only existed for about a year.


Accuracy? That's up to each rifle, as usual.
My rifle shoots Armscor (and Armscor Fiocchi) and Winchester Supreme better than anything else. It still does well with some of the CCI loads, but Winchester Supreme comes out on special occasions and Armscor is my bread and butter. (Whether 45 gr SP or 40 gr HP. It's the same bullet and they shoot the same at rimfire distances. One just has 5 gr of lead missing from the little dimple in the nose.)

 

[44 AMP]

Accuracy testing in a single rifle shows what that rifle will do, and not do. TO create any kind of meaningful pattern about what the ammo does, overall, the same ammo will need to be tested in multiple rifles, enough to create what is called "significant data".

How many is that? I have no idea. I don't think 2 rifles would be enough. 10 might be...

And, that's something out of reach for most of us. Might be possible (with enough ammo) as a smallbore club "project" though.

 

[taylorce1]

I do not know what the next incarnation of Remington .22 WMR will be. The last production era had CCI contracted to make it, but I haven't seen any news or product since the bankruptcy.

I don't know who is making it either but I have a brick of Premier 33 grain on the way. I'm guessing it will be current production as I only paid $130 for it.

 

[berettaprofessor]

For some reason, the 'Champion Target' has issues with wax - at least for me. Give it 5-6 years, and it becomes difficult to chamber. Let it sit for 10 years, and the wax is so swollen that it starts flaking and peeling

I'm sorry, I should have been more specific because its worse than that....the stuff I measured is the Champion "Value" pack...the 525 round copper-plated 36 grain crap. Which is why I'm so surprised it was consistent. Age these rounds and all you get is blackened/tarnished copper stuff you're afraid to shoot.