Wandering fired brass
All commercial brass, a few free-range ones got in w/yr own empties?? Check the case length and trim and chamfer i & o if over spec, then chamber all the empties in yr rifle; the ones yr bolt won't close on will need FL resizing. Other than that you're home free.
The not-yr-rifle cases will have slight accuracy issues--as will the FL resized ones--but if you're not segregating yr brass by manufacturer and keeping the lots of brass separate you're not being picky enough for the odd brass to make itself a notable problem.
Once the brass been fired in yr rifle, of course, you can just neck-size it, reload it, and shoot it, ten times over or more.
Check all fired brass, of course, for any cracks or other damage, be it from your private lot or free range brass.
God Bless America