I have about 1000 rounds of brass.. All range pick up, once fired as they were crimped. LC, Wolf, Federal, Norma, Hornady, PMC, Starline, Remington, and Winchester that all weigh right at 92 gr + or - a grain. Most of it is LC or Federal .

Then I have some CBC brass that weighs 101 gr and some USA A and GFL brass that weigh 97 gr.Why would that CBC brass be so much more? Would it be 5.56 brass that is thicker in the head?

More curious than anything. I don't plan to use those three head stamps. If I do,will keep separate.

LC is all 5.56 loads so that shoots down your hypothesis right there.

Truth is, is just a difference between manufacturers.
No need to think about it beyond that.

I spent a lot of time weighing .223 brass this summer (COVID boredom); the vast majority was 92 - 94 grains. But there were some anomalies like a few FC (visually indistinguishable from other FC) and some foreign manufacture that were a lot heavier. Being rather OCD, I turned the heavier stuff into .300 BLK and then measured the new necks, some were quite a bit thicker than others, but there was ton rhyme or reason to them. As AS said, different lots and different manufacturers.

Could be tooling or composition or both.

I've been dumb about it for a long time...

I separate ALL my brass into lots with the same head stamp and just go out and shoot it.. when it comes to even the 223...

being dumb, I've never had a problem...

ya gotta be using pretty fast powder to blow up a 223 case...

not saying people don't do it every day.. but a little common sense goes a long way at the reload bench...

I'd go ahead and take the 92 weight brass, work up a load with the most numerous headstamp as a "control." Then maybe load up enough of each outlier headstamp to shoot mixes of five, as well as fives of each headstamp, see if there's any group-size anomalies. But if the case weights are same-same, and the case prep/trim is same-same, it probably won't matter very much, maybe not at all.

As for the heavies, maybe set those aside for "autoloader" batch?

I have loaded THOUSANDS of mixed range brass with no issue and maintain great accuracy. Grab em and load em I say. No future is weighing this brass or over thinking it. Just have a good process to sewage and size, trim if necessary and get on with it

Exactly, KISS method always works

That's true, but it is always better to know what you have. I don't load to the max, but for some one that does, 10 gr weight difference can get you in trouble.Years ago,I substituted some military brass for commercial in a .308, using the same load. .Almost didn't get the bolt open. Sometimes KISS can turn around and kiss you in the butt. Caution is always better than ignorance and that is why I asked.

After tumbling, I sort range pickup brass by headstamp, and further sort by year if there is a year listed on the head stamp. May be overkill, but I've not blown myself up yet, and I load to the hot end usually.

I've further sorted several hundred FC cases by weight, sticking to a fairly narrow range, but can't really tell a difference in accuracy. Some of the best range brass I'm currently running in a 223 bolt gun is Fiocci GFL headstamp, and the weight of that brass is all over the place. YMMV

I know which head stamps are usually in the 97-100+ range and I keep them separate from the 90-95 gr brass.
Close enough for me, I load different bullets and loads in the heavier brass just so I can tell at a glance.
it gives me an excuse to have a couple of different types of loads. I found Nosler brass to be heavy also.

I've got a bucket full of range pickup stuff that is all processed and ready to go. But I'll never use it myself. I'll probably sell it all and buy back LC brass because that's all I ever use in my ARs.

I used to sort brass like some of you all but I got tired of that real fast. Sticking to one particular brand makes it a little easier.

Like you I quit worrying about the minutiae, many many years ago. I do not mix headstamps however.

I have had lightweight .223 brass come within 1.4 grains of Ball C-2 powder capacity, measured to the top of the case when compared to heavy .223 brass that had been fire-formed into .223 improved. Take a look at the tables of .223 brass weight and case capacity published in this article. https://www.accurateshooter.com/cartridge-guides/223rem/

Lapua makes outstanding brass. However, the author found a considerable difference between different lots of the high quality Lapua brand brass. I imagined the same thing can happen within and between other brands of brass.