So is this why I'm seeing a lot of variation for brass then? You can get unknown brass with unknown number of uses remaining, i.e. picking it up at range or buying 2nd hand, or brand new brass and assume an average number of uses remaining (i'm guessing it would also depend on your load?)
So to track my cost for brass, I'd have to make the decision between cheaper and unknown vs more expensive and new/known, then approximate I guess?
I was just planning on buying factory ammo to start and picking up my own brass.
I think you have got good analysis going - for brass though - I found is sort of "wild card". How long the brass lasts is a bit about the loads that you chose - hotter loads, the brass dies sooner - mild loads, the brass might never die, with periodic case neck annealing.
I have pile of once fired factory 22-250 Winchester brass from neighbour - I processed about 180 brass - I think was 4 found that were not longer useable - the necks were split - and I do not doubt all was factory rounds, still with the factory primers in there - that guy does not reload, and has never had "re-loads" done for him. His "stash" was so mixed up that I do not know if those cracked necks were from same box of ammo, or were random across the bunch that he brought over.
One of the "variations" that you discover in brass - how hard versus how "springy" is it? From some factories is quite hard and rigid - others quite soft and springy - as home guy you can anneal case necks and make them soft and springy again - they got "hard" by being "worked" - expanded when fired, squeezed down when resized, then slightly expanded again as a bullet is seated.
I recently went through a bag of 100 Winchester new brass for 22-250 - in the "red label" bag. Older stuff was in blue label bags. Out of the 100 factory new ones - about 20 or more had issues - visible folds on shoulders; either cracks or potential cracks on the neck; about a dozen had necks so deformed that they would not chamber into my rifle - as if a tooling had been left within the case neck as the case tilted over - to make like a "spigot" or "pitcher pour" deformity (going "out") on the case neck. With re-sizing, etc., I have the full 100 now fit to reload - but not sure whether some of them will survive a first or second firing - I do not think those necks will last.
My previous experience, until these "new" Winchester cases, was that the primer pocket will stretch - until you can virtually press a primer into place with your thumb, if you let it go that far - loose primer pockets retired probably 90% of the brass that I threw out, split necks probably the rest.
I have received brass that was sold as "once fired" - all shiny nice from a stainless pin tumble, alleged to be "pre-processed" and ready to reload - except primer pockets really sloppy - is no way, to me, that was "once fired" brass. So, lately, I have tried to limit my purchases to mil-surp brass with original primers still crimped in place - I have the gizmos to remove those primers, chamfer those primer pockets and stainless pin tumble that brass if I want to. The alternate was to buy factory new brass, as I have been doing since 1980's - except this last bag of red label Winchester has really given me pause to consider how "crappy", to me, is the stuff being sold as "factory new" bulk brass. I have never owned Lapua or Nosler brass - I suspect they are several steps better. I doubt that I had seen that many previous issues in thousands of cases from Remington, from Winchester Blue Label, from PPU - as I found in this one bag of 100. And I have two more bags of it to go, yet.
