I'm not thrilled getting into these "rim thickness" discussions because I've spent a lot of time and not a small amount of money measuring rim thickness and convincing myself rim thickness has nothing to do with precision. I haven't convinced anyone else yet but here goes anyway.
I bought an $85.00 Bald Eagle rim thickness gauge and measured the following high end rounds.

Note that none of the measurements come close to the lowest headspace anyone uses of .043. Also note that some of the brands were then fired through a chronograph and the velocity recorded.
Next as a range manager, I picked up a lot of live rounds and measured the rim thickness on them. These are basically bulk ammo.
Note that none of those are above .039, still below the threshold of .043. But the STD is larger than the high end stuff except the Win Xpert and I guess that is to be expected. What is surprising is these rounds are not necessarily from the same lot and as you can see in the first pic, even in high end ammo the avg varies from lot to lot.
The reason I did the velocity test in the first pic is because I did a correlation plot of the rim thickness versus velocity and found no correlation. Rim thickness does not equate to precision.
Now here is the interesting part about measuring rim thickness even with a highly regarded Bald Eagle Gauge. I took one round of each below and marked 4 quadrants on the rim and took three measurement on each of the 4 quadrants. I did this by rotating the round 1/4 turn for each measurment.
Except the Eley Match I got .001 spread on the same round. So what are you measuring.