Jaybrown--Free range brass is a great boon to the beginning reloader. Any brass you pick up @ the range is
almost guaranteed to be store-bought and once-fired. Why? Simple: Reloaders save their brass to take home and reload once again. Non-reloaders buy their ammo at Wally World, shoot it up, leave the brass @ the range, and repeat next week.
Don't futz with aluminum cases, Berdan primed cases, steel cases, or anything headstamped "Amerc." If it's real brass, and Boxer primed, it's fair game. The other stuff can be done, but it's a headache and there's plenty of good brass so why bother.
If a reloader decides a given lot of brass is all tired and worn out, he doesn't take it to the range to dump it, nor does he load it up "one last time." It goes directly to his scrap brass bucket.
Every few years I take all the scrap brass I have to a metal dealer and get a little cash.
And you CAN pretty much tell once-fired--it has no marks on it from the sizing die. No gas leak mark around the primer. No cracked necks, no split bodies. No ironed-out ejection dents. No stains nor burn marks. Primers not backed out nor excessively flattened. And you're pretty much good to go.
So you inspect each piece for flaws as Ball 3006 indicated, and go ahead and load 'em up and shoot 'em. You'll need a caliper, a case trimmer and chamfer/debur set, and a flash hole uniformer is good too. Get the specs for each cartridge from yr reloading manual.
If the Lyman manual says don't use fired brass they were told to say so by their legal department. Ah, here we are--Lyman's 48th edition, pg 22: "CAUTION: Never load cartridge cases from an unkown source, i. e. cases picked up at a range or sold as once-fired brass. Use only brand new brass or cases obtained as the result of firing factory ammo in your firearm...." Yeah, right.
Is there some risk? Of course! There is risk in everything we do in this life, and we none of us will get out of here alive. OTOH, with brand-new brass, can you internally inspect each piece and determine that there are no metal flaws nor weak spots?? Of course not. Is the risk of using free range brass worth it for YOU? That's for you to decide. But if you do, you'll have a lot of company.