I occasionally order some "range brass" online and it's almost always advertised as "once-fired mixed brass." I'm guessing the common source is ranges that sweep up every now and then so mixed headstamps are expected. Generally a good deal if you're not desperate and can be patient for decent prices. Of course there's no way to know for certain how many times a cartridge case has been reloaded but certainly some of my purchases have been reloaded more than "once." Sorting and inspection is always a good idea.
Just took delivery of some .45 Colt, 9x19mm, and .32 H&R Mag brass. Kind of an interesting assortment in the "lots" of brass.
The 100 cases of .32 H&R Mag were 95% Starline brass. It brings up the question in my head of why brass, almost exclusively used by hand loaders, and in revolvers, would end up on the range floor? Am I missing something or is this a mystery? It looks to be in good shape.
Also two of the 200 .45 Colt cases were balloonheads. I know about them but have never actually held one in my paws. I'll just keep them in the collection as they won't insert into a .45 Colt shellholder in my inventory and I likely wouldn't reload them anyway.
I buy 9mm brass by the short ton every now and then because my loss rate approaches 20% when the grass gets high on our ranch range.
Two balloonhead .45 Colt cartridges
Compared to "regular" .45 Colt
Hopefully you can see the recess around the primer pocket indicating a balloonhead cartridge.